News from Industry

Kamailio v4.2.5 Released

miconda - Tue, 05/19/2015 - 09:43
Kamailio SIP Server v4.2.5 stable is out! This is a minor release including fixes in code and documentation since v4.2.4. Don’t worry about upgrading – the configuration file and database compatibility is preserved.Kamailio (former OpenSER) v4.2.5 is based on the latest version of GIT branch 4.2, therefore those running previous 4.2.x versions are advised to upgrade. There is no change that has to be done to configuration file or database structure comparing with older v4.2.x.Resources for Kamailio version 4.2.5Source tarballs are available at:Detailed changelog:Download via GIT: # git clone git:// kamailio
# cd kamailio
# git checkout -b 4.2 origin/4.2Binaries and packages will be uploaded at:Modules’ documentation:What is new in 4.2.x release series is summarized in the announcement of v4.2.0:Looking forward to meeting many of you at Kamailio World 2015 next week!

FreeSWITCH Week in Review (Master Branch) May 9th-May 16th

FreeSWITCH - Tue, 05/19/2015 - 00:12

Hello, again. This passed week in the FreeSWITCH master branch we had 14 commits. Our feature for this week is the addition of limit backend to mod_mongo. It needs some testing, so go check it out.

Join us on Wednesdays at 12:00 CT for some more FreeSWITCH fun! And head over to to learn more about FreeSWITCH support.

New features that were added:

  • FS-7557 [mod_mongo] Add limit backend

The following bugs were squashed:

  • FS-7552 [mod_amqp] Fixed a segfault on unload and when no connections were valid
  • FS-7463 [mod_sofia] Conditionally allow intercept of replaced call-id when processing replaces header
  • FS-7557 [mod_mongo] Fixed a crash when doing ‘limit_usage mongo foo bar’
  • FS-7545 [mod_opus] Fixed RTP timestamps to prevent un-needed resampling when transcoding
  • FS-7184 [mod_spandsp] Fixed a fax buffer overflow in t38 on failure condition with some fax machines
  • FS-7546 [mod_spandsp] Fixed a crash when sending a fax when built using clang compiler

W3C ORTC CG Meeting 8 - Wed, 05/13/2015 - 08:11

ORTC CG Meeting 8 will be held on May 13 at 10am – Pacific Daylight Time.

Where: Online WebRTC Enable Meeting via Jitsi ( Reverted to Google Hangouts


FreeSWITCH Week in Review (Master Branch) May 2nd-May 8th

FreeSWITCH - Mon, 05/11/2015 - 21:23

Hello, again. This passed week in the FreeSWITCH master branch we had 6 commits. Some more work was done to mod_amqp this week as well as some bug fixes.

Join us on Wednesdays at 12:00 CT for some more FreeSWITCH fun! And head over to to learn more about FreeSWITCH support.

New features that were added:

  • FS-7526 Add enable_fallback_format_fields for mod_amqp producer profiles if the profile param is set and create the amqp exchange on the first startup of a clean platform.

The following bugs were squashed:

  • FS-7425 Fixed a bug when using a cert with missing dhparams resulting in a segfault.
  • FS-7523 [mod_json_cdr] Fixed a segfault caused by a missing config file.
  • FS-7357 FAX now tolerates EOP and PPS messages being incorrectly echoed.

Facebook Messenger likes WebRTC

webrtchacks - Mon, 05/11/2015 - 12:37

Two weeks ago Philipp Hancke,  lead WebRTC developer of Talky and part of the &yet‘s WebRTC consulting team, started a series of posts about detailed examinations he is doing on several major VoIP deployments to see if and how they may be using WebRTC. Please see that post on WhatsApp for some background on the series and below for another great analysis – this time on Facebook Messenger. {“editor”: “chad“}


Last week, Facebook announced support for video chats in their Messenger app. Given that Messenger claims to account for 10% of global mobile VoIP traffic, this made in a very interesting target for further investigation. As part of the series of deconstructions, the full analysis (another fifteen pages, using the full range of analysis techniques demonstrated earlier) is available for download here, including the wireshark dumps.


Facebook Messenger likes WebRTC

Facebook Messenger is an extremely popular messaging and communications app. It works in Chrome / Firefox and Opera as well as Android and iOS. The mobile versions use the library and Messenger is optimized heavily for mobile use cases:

  • Instead of DTLS, the older SDES encryption scheme is used between mobile clients. While not offering features such as perfect forward secrecy, it provides faster call setup time.
  • The audio codec depends on platform and peer. Opus, iSAC and iSAC Low Complexity (LC) are used, with a packetization that prefers fewer, larger packets.
  • VP8 is used as video codec on web, iOS and Android. Interestingly, Facebook chose VP8 over H.264 for iOS, even though VP8 has no hardware acceleration capability on Apple iOS devices.
Comparison with WebRTC  Feature WebRTC/RTCWeb Specifications Messenger SDES MUST NOT offer SDES uses SDES between mobile clients, DTLS with browsers ICE RFC 5245 RFC 5245 with some old google quirks TURN usage used as last resort TURN and old Google relay Audio codec Opus or G.711 Opus, iSAC, ISAC Low Complexity Video codec VP8 or H264 VP8 WebRTC fulfilling its promise: No plugins required

Back in 2011, Facebook launched Skype-powered video calling. It used a plugin. The need for a plugin is now gone, probably along with other parts of the integration as described in this announcement. Most platforms are supported without requiring users to install something. WebRTC is starting to fulfill its promise: no plugins needed.

The WebRTC rollout at Facebook has been done gradually, starting in early 2015. Chad Hart was one of the first people to notice in mid-January. I took a quick look and was not very impressed by what I found. Basically it was a simple 1-1 webchat akin to Google’s apprtc sample.

Recently, there has been a lot of news on Facebook’s Messenger. They launched as a standalone website with support for voice and video between browsers. As Tsahi Levent-Levi pointed out already, it is using WebRTC.

On the mobile side, the Messenger client had been voice only. Video calling is available in the apps as well. All of this warrants a closer look. With WhatsApp and Messenger coming from the same company, we were expecting similarities, making this report easy. Well… that’s not how it ended up.

It turns out that unlike WhatsApp:

  • Messenger uses the library provided by Google
  • VP8 video codec is used for video calls
  • Choice of the audio codec, which includes ISAC and Opus, varies based on the devices used and the other party in the call
  • DTLS is used for encrypting the media between the app and the browsers
  • DTLS is not used in calls between two mobile devices (surprisingly)

While Messenger looks pretty standard, there are quite a number of optimizations here. Some gems are hidden to anyone glancing through the details. Chrome’s webrtc-internals are easily available and were used in the first scenarios tested. It allows looking at the implementation from a number of different angles, all the way from the captured packets, via the signaling protocol and up to the WebRTC API calls.

The iOS application offers a number of non-standardized codecs. In particular, when calling Chrome the iSAC audio codec will be used. Opus is used with Firefox, which does not implement iSAC. In both cases, the app tweaks the codec usage by sending larger frames than the browser. That is quite an interesting hack reminiscent of the WhatsApp behaviour of switching to a larger packetization. I can only speculate that this may show larger packets to be more robust on wireless networks?

Calls between two mobile devices turn out to be more interesting. Here, the optimizations for calling a browser come to bear fully.

Currently, video calls are only supported between either mobile devices or browsers, which will surely change soon. VP8 is used as the codec.

Unlike WhatsApp, Messenger can be run on multiple devices. So when calling someone who is logged in on multiple devices, all devices ring. This is nice behavior, as it allows the called user to choose where to take the call. This makes a lot more sense than previous approaches, e.g. Google Talk attempting to let the caller determine the recipients “most available device” from a UX point of view. In a world where mobile devices are disconnected frequently and need to be woken up via push messages, this is even more important than it was a decade ago.


The most important takeaway is that instead of using DTLS, Messenger uses the older SDES encryption scheme between two mobile clients. This means media can flow as soon as ICE is done, eliminating a round-trip for the DTLS handshake. This shows a desire to reduce the session startup time, similar to what we saw with WhatsApp.
The widely known downside of that is that the encryption keys are sent via the signaling servers and can be used to retroactively decrypt traffic. Government agencies will surely rejoice at the news of this being applicable to 10% of the mobile VoIP traffic…


{“author”: “Philipp Hancke“}

Want to keep up on our latest posts? Please click here to subscribe to our mailing list if you have not already. We only email post updates. You can also follow us on twitter at @webrtcHacks for blog updates and news of technical WebRTC topics or our individual feeds @chadwallacehart@reidstidolph, @victorpascual and @tsahil.

The post Facebook Messenger likes WebRTC appeared first on webrtcHacks.

New Kamailio Module: Erlang

miconda - Mon, 05/11/2015 - 09:42
Before freezing the development for next major release – Kamailio v4.3.0 – several modules and other relevant additions were pushed in a rather short period of time to git repository. Now, we are trying to look briefly at few of them in a series of posts in order to let everyone know about them.First to talk about it is the erlang module, contributed by Seudin Kasumovic of Bicom Systems. Erlang is a functional programming language tightly related to telecom environment, with built-in support for concurrency, distribution and fault toleranceThe module enables interaction of Kamailio with Erlang nodes, allowing to send and receive Erlang messages as well as RPC calls between each other. You can read more about it at:Seudin will also present at Kamailio World Conference how this module can be used and its benefits for scalability and reliability.

ClueCon Weekly May 6th, 2015!

FreeSWITCH - Wed, 05/06/2015 - 21:03

Check out the weekly conference call to see the latest news!

Kamailio World 2015 – Grants for Students

miconda - Tue, 05/05/2015 - 14:17
Given the roots and the tight relation of Kamailio project with the academic environment, we are offering three seats at Kamailio World Conference, May 27029, 2015, in Berlin, to students enrolled in universities or research institutes (both bachelor and PhD programs qualify).Last year we tried it locally with the universities in Berlin and this year we want to extend it, as there might be young people interested to travel a bit and attend the event.If you are a student and want to participate, email to . Participation to
all the content of the event (workshops, conference and social event) is free, but you will have to take care of expenses for traveling and accommodation. Write a short description about your interest in real time communications and what is the university or the research institute you are affiliate to.Also, if you are not a student, but you are in touch with some or have access to students forums/mailing lists, it will be very appreciated if you forward these details.More information about Kamailio World is available on the web site:Looking forward to meeting many of you in just few weeks in Berlin!

Simulating NAT with two Linux boxes

TXLAB - Tue, 04/28/2015 - 17:20

I needed to test some master-slave software in a situation that the master communicated to the slave over NAT (master’s IP address was replaced with the firewall’s external address), and then NAT would be removed, keeping master and slave addresses the same, but the slave would see the master directly.

This is the test scenario that worked on my desk, without having to add any routing to the LAN.

atom02 is the computer that emulates the slave system. It is connected back-to-back to alix102, and has only one IP address to communicate to:

ip link set dev eth0 up ip addr add dev eth0

alix102 is a Linux box with multiple Ethernet ports: eth0 is connected to my home LAN and has a DHCP address Also eth1 ( is connected directly to atom02.

The following configuration makes alix102 answer to ARP requests for and forward packets to atom02, replacing the source address with Also atom02 can make an SSH connection to and it will be connected to another box in the LAN that emulates the software master (

# enable IP forwarding echo 1 > /proc/sys/net/ipv4/ip_forward # Bring up eth1 ip link set dev eth1 up ip addr add dev eth1 # Enable proxy ARP on eth0 echo 1 > /proc/sys/net/ipv4/conf/eth0/proxy_arp # Set up the NAT translation iptables -t nat -A POSTROUTING -o eth1 -j SNAT --to iptables -t nat -A PREROUTING -p tcp --dport 3022 -i eth1 -j DNAT --to

After that, atom02 can be re-connected directly into the LAN, keeping the address with /24 network mask, and the software can be tested with direct communication. Alix102 has to be disconnected from the LAN, so that it does not pollute it with proxy ARP responses.

Filed under: Networking Tagged: linux

Linux reboot freezes on Acer Aspire One

TXLAB - Tue, 04/28/2015 - 11:16

I needed to install CentOS 6 on one an old Acer Aspire One notebook (with Intel Atom CPU) for some software testing. The problem is, that it could not perform a reboot, and I needed to press the power button every time. These instructions for reboot=X parameter for kernel did not help at all.

What really helped, is `kernel-ml` package from repositories. At the moment of writing, it was version `4.0.0-1.el6.elrepo.x86_64`.

Keep in mind that after installing kernnel-ml package, you need to edit /etc/grub.conf and make this new kernel as default. No additional boot options are required.

Filed under: Hardware Tagged: linux

Kamailio World 2015 – The Schedule

miconda - Mon, 04/27/2015 - 17:00
It is one month till the start of Kamailio World 2015, time has passed very fast since we announced the event, accelerated by April filled with many public holidays.The first draft of the schedule is now available, as usual, expect many speakers to tune the content of their presentation along the way to the day of the talk, to surprise the audience with challenging concepts and visions.At this edition we were pleasely surprised by the number of submissions, but it was an extremely hard task to select the sessions. To accommodate as much as possible, we are introducing the lightning talks, two of 10 minutes each, to give the opportunity to present shortly about interesting ideas or updates of applications used in Kamailio and VoIP eco-system.The two days of conference are filled with 28 sessions, the event being completed with 5 technical workshopsduring the pre-conference day. Several exhibitors will be available during the conference days with showcases of their products or solutions, ready with many demos on site.We are very grateful to our sponsors, which made possible to bring again a consistent number of speakers, ensuring first class quality content for the entire event.In about 4 weeks, we will be ready to welcome you in the beautiful city center of Berlin. Don’t miss the opportunity to attend this event, it is unique across Europe, bringing open source and real time communications industry together, bridging flexibility innovation with telecommunication businesses. It is now the right time to register!See you in Berlin at the end of May!

Kamailio v4.3 – Development Frozen

miconda - Thu, 04/23/2015 - 11:10
The development (aka master) branch of Kamailio now enter the pre-release phase for version 4.3.0. No new features are allowed to be pushed to GIT master branch until we create a dedicated branch for 4.3 (expected to be in about 4 weeks or so).The focus moves now on testing the code, to get it in a stable, rock solid state at the time of release. We hope to get many people from the community involved in testing. If you want to get involved and need assistance about what and how to do it, please don’t hesitate to write to mailing lists. The first step is to get Kamailio installed from sources, details at:Stay tuned for updates to the wiki pages with guidelines for migration from 4.2 to 4.3 as well as what is new in version 4.3.The release of v4.3.0 is expected to be out few weeks after Kamailio World Conference — more or less about mid of June 2015.

WebRTC Meetup – Vancouver - Thu, 04/23/2015 - 06:12

Vancouver is one of the hotbeds for IP communication technology and is home to many developers. With the advent of WebRTC, integration of voice and video chat into almost any application is within reach but as always, there are always pitfalls. Sounds like a great reason to start a WebRTC meetup in Vancouver!

As of today Vancouver now has its own WebRTC meetup group. If you are interested in linking up and talking to like-minded RTC geeks implementing real time comm using WebRTC please join and let’s get together. We will also be looking for meetup facilities & sponsors (snacks, drinks etc.).

I am thinking our first meetup will be in May sometime, not sure on exact dates yet.

Agenda and topic for the first meeting is wide open. Topics like, “WebRTC 101″ or “Dos and Don’ts” come to mind, but we can decide on that when we have heard from some active members.

We will also be bringing in some live guests from time to time via what else, WebRTC!

Hope to see you soon!


What’s up with WhatsApp and WebRTC?

webrtchacks - Wed, 04/22/2015 - 17:14

One of our first posts was a Wireshark analysis of Amazon’s Mayday service to see if it was actually using WebRTC. In the very early days of WebRTC, verifying a major deployment like this was an important milestone for the WebRTC community. More recently, Philipp Hancke – aka Fippo – did several great posts analyzing Google Hangouts and Mozilla’s Hello service in Firefox. These analyses validate that WebRTC can be successfully deployed by major companies at scale. They also provide valuable insight for developers and architects on how to build a WebRTC service.

These posts are awesome and of course we want more.

I am happy to say many more are coming. In an effort to disseminate factual information about WebRTC, Google’s WebRTC team has asked &yet – Fippo’s employer – to write a series of publicly available, in-depth, reverse engineering and trace analysis reports. Philipp has agreed to write summary posts outlining the findings and implications for the WebRTC community here at webrtcHacks. This analysis is very time consuming. Making it consumable for a broad audience is even more intensive, so webrtcHacks is happy to help with this effort in our usual impartial, non-commercial fashion.

Please see below for Fippo’s deconstruction of WhatsApp voice calling.

{“editor”: “chad“}


Philipp Hancke deconstructs WhatsApp to search for WebRTC


After some rumors (e.g. on TechCrunch), WhatsApp recently launched voice calls for Android. This spurred some interest in the WebRTC world with the usual suspects like Tsahi Levent-Levi chiming in and starting a heated debate. Unfortunately, the comment box on Tsahi’s BlogGeek.Me blog was too narrow for my comments so I came back here to webrtchacks.

At that point, I had considered doing an analysis of some mobile services already and, thanks to support from the Google WebRTC team, I was able to spend a number of days looking at Wireshark traces from WhatsApp in a variety of scenarios.

Initially, I was merely trying to validate the capture setup (to be explained in a future blog post) but it turned out that there is quite a lot of interesting information here and even some lessons for WebRTC. So I ended up writing a full fifteen page report which you can get here. It is a long story of packets (available for download here) which will be very boring if you are not an engineer so let me try to summarize the key points here.


WhatsApp is using the PJSIP library to implement Voice over IP (VoIP) functionality. The captures shows no signs of DTLS, which suggests the use of SDES encryption (see here for Victor’s past post on this).  Even though STUN is used, the binding requests do not contain ICE-specific attributes. RTP and RTCP are multiplexed on the same port.

The audio codec can not be fully determined. The sampling rate is 16kHz, the codec bandwidth of about 20kbit/s and the bandwidth was the same when muted.

An inspection of the binary using the strings tool shows both PJSIP and several strings hinting at the use of elements from the voice engine such as the acoustic echo cancellation (AEC), AECM, gain control (AGC), noise suppression and the high-pass filter.

Comparison with WebRTC  Feature WebRTC/RTCWeb Specifications WhatsApp SDES MUST NOT offer SDES probably uses SDES ICE RFC 5245 no ICE, STUN connectivity checks TURN usage used as last resort uses a similar mechanism first Audio codec Opus or G.711 unclear, 16khz with 20kbps bitrate Switching from a relayed session to a p2p session

The most impressive thing I found is the optimization for a fast call setup by using a relay initially and then switching to a peer-to-peer session. This also opens up the possibility for a future multi-party VoIP call which would certainly be supported by this architecture. The relay server is called “conf bridge” in the binary.

Lets look at the first session to illustrate this (see the PDF for the full, lengthy description):

  1. The session kicks off (in packet #70) by sending TURN ALLOCATE requests to eight different servers. This request doesn’t use any standard STUN attributes which is easy to miss.
  2. After getting a response the client is exchanging some signaling traffic with the signaling server, so this is basically gathering a relayed candidate and sending an offer to the peer.
  3. Packet #132 shows the client sending something to one of those TURN servers. This turns out to be an RTCP packet, followed by some RTP packets, which can be seen by using Wiresharks “decode as” functionality. This is somewhat unusual and misleading, as it is not using standard TURN functionality like send or data indications. Instead, it just does raw RTP on that.
  4. Packet #146 shows the first RTP packet from the peer. For about three seconds, the RTP traffic is relayed over this server.
  5. In the mean time, packet #294 shows the client sending a STUN binding request to the peer’s public IP address. Using a filter (ip.addr eq and ip.addr eq and (udp.port eq 45395 and udp.port eq 35574)  clearly shows this traffic.
  6. The first response is received in packet #300.
  7. Now something really interesting happens. The client switches the destination of the RTP stream between packets #298 and #305. By decoding those as RTP we can see that the RTP sequence number increases just by one. See this screenshot:

Now, if we have decoded everything as RTP (which is something Wireshark doesn’t get right by default so it needs a little help), we can change the filter to rtp.ssrc == 0x0088a82d  and see this clearly. The intent here is to try a connection that is almost guaranteed to work first (I used a similar rationale in the minimal viable SDP post recently even) and then switch to a peer-to-peer connection in order to minimize the load on the TURN servers.

Wow, that is pretty slick. It likely reduces the call setup time the user perceives. Let me repeat that: this is a hack which makes the user experience better!

By how much is hard to quantify. Only a large-scale measurement of both this approach and the standard approach can answer that.

Lessons for WebRTC

In WebRTC, we can do something similar, but it is a little more effort right now. We can setup the call with iceTransports: ‘relay’ which will skip host and server-reflexive candidates. Also, using a relay helps to guarantee the connetion will work (in conditions where WebRTC will work at all).

There are some drawbacks to this approach in terms of round-trip-times due to TURN’s permission mechanism. Basically when creating a TURN-relayed candidate the following happens (in Chrome; Firefox’s behavior differs slightly):

  1. Chrome tries to create an allocation without authentication
  2. the TURN server asks for authentication
  3. Chrome retries to create an allocation with authentication
  4. the TURN server tells chrome the address and port of the candidate.
  5. Chrome signals the candidate to the JavaScript layer via the onicecandidate callback. That is two full round-trip times.
  6. after adding a remote candidate, Chrome will create a TURN permission on the server before the server will relay traffic from the peer. This is a security mechanism described here.
  7. now STUN binding requests can happen over the relayed address. This uses TURN send and data indications. These add the peer’s address and port to each packet received.
  8. when agreeing on a candidate, Chrome creates a TURN channel for the peer’s address which is more efficient in terms of overhead.

Compared to this, the proprietary mechanism used by Whatsapp saves a number of roundtrips.

this is a hack which makes the user experience better!

If we started with just relay candidates, then, since this hides the IP addresses of the parties involved from each other, we might even establish the relayed connection and do the DTLS handshake before the callee accepts the call. This is known as transport warmup, it reduces the perceived time until media starts flowing.

Once the relayed connection is established, we can call setConfiguration (formerly known as updateIce; which is currently not implemented) to remove the restriction to relay candidates and do an ICE restart by calling createOffer again with the iceRestart flag set to true. This would trigger an ICE restart which might determine that a P2P connection can be established.

Despite updateIce not being implemented, we can still switch from a relay to peer-to-peer today. ICE restarts work in Chrome so the only bit we’re missing is the iceTransports ‘relay’ which just generates relay candidates. Now the same effect can be simulated in Javascript by dropping any non-relay candidates during the first iteration. It was pretty easy to implement this behaviour in my favorite sdp munging sample. The switch from relayed to P2P just works. The code is committed here.

While ICE restart is inefficient currently, the actual media switch (which is hard) happens very seamlessly.


In my humble opinion

Whatsapp’s usage of STUN and RTP seems a little out of date. Arguably, the way STUN is used is very straightforward and makes things like implementing the switch from relayed calls to P2P mode easier. But ICE provides methods to accomplish the same thing, in a more robust way. Using a custom TURN-like functionality that delivers raw RTP from the conference bridge saves some bytes’ overhead for TURN channels, but that overhead is typically negligible.

Not using DTLS-SRTP with ciphers capable of perfect forward secrecy is a pretty big issue in terms of privacy. SDES is known to have drawbacks and can be decrypted retroactively if the key (which is transmitted via the signaling server) is known. Note that the signaling exchange might still be protected the same way it is done for text messages.

In terms of user experience, the mid-call blocking of P2P showed that this scenario had been considered which shows quite some thought. Echo cancellation is a serious problem though. The echo cancellation is capable of a much better job and seems to be included in the binary already. Maybe the team there would even offer their help in exchange for an acknowledgement… or awesome chocolate.


{“author”: “Philipp Hancke“}

Want to keep up on our latest posts? Please click here to subscribe to our mailing list if you have not already. We only email post updates. You can also follow us on twitter at @webrtcHacks for blog updates and news of technical WebRTC topics or our individual feeds @chadwallacehart@reidstidolph, @victorpascual and @tsahil.

The post What’s up with WhatsApp and WebRTC? appeared first on webrtcHacks.

The WebRTC Troubleshooter:

webrtchacks - Mon, 04/20/2015 - 09:00

WebRTC-based services are seeing new and larger deployments every week. One of the challenges I’m personally facing is troubleshooting as many different problems might occur (network, device, components…) and it’s not always easy to get useful diagnostic data from users.

troubleshooting (Image source: google)

Earlier this week, Tsahi, Chad and I participated at the WebRTC Global Summit in London and had the chance to catch up with some friends from Google, who publicly announced the launch of This is great diagnostic tool but, to me, the best thing is that it can be easily integrated into your own applications; in fact, we are already integrating this in some of our WebRTC apps.

Sam, André and Christoffer from Google are providing here a brief description of the tool. Enjoy it and happy troubleshooting!

{“intro-by”: “victor“}

The WebRTC Troubleshooter: (by Google) Why did we decide to build this?

We have spent countless hours debugging things when a bug report comes in for a real-time application. Besides the application itself, there are many other components (audio, video, network) that can and will eventually go wrong due to the huge diversity among users’ system configurations.

By running small tests targeted at each component we hoped to identify issues and create the possibility to gather information on the system reducing the need for round-trips between developers and users to resolve bug reports.

Test with audio problem

What did we build?

It was important to be able to run this diagnostic tool without installing any software and ideally one should be able to integrate very closely with an application, thus making it possible to clearly identify bugs in an application from the components that power it.

To accomplish this, we created a collection of tests that verify basic real-time functionality from within a web page: video capture, audio capture, connectivity, network limitations, stats on encode time, supported resolutions, etc… See details here. 

We then bundled the tests on a web page that enables the user to download a report, or make it available via a URL that can be shared with developers looking into the issue.

How can you use it?

Take a look at and find out what tests you could incorporate in your app to help detect or diagnose user issues. For example, simple tests to distinguish application failures from system components failures, or more complex tests such as detecting if the camera is delivering frozen frames, or tell the user that their network signal quality is weak.

You are encouraged by us to take ideas and code from GitHub and integrate similar functionality in your own UX. Using should be part of any “support request” flow for real-time applications. We encourage developers to contribute! 

In particular we’d love some help getting a uniform getStats API between browsers. repo

What’s next?

Working on adding more tests (e.g. network analysis detecting issues that affect audio and video performance is on the way).

We want to learn how developers integrate our tests into their apps and we want to make them easier to use!

{“authors”: [“Sam“, “André“, “Christoffer”]}

Want to keep up on our latest posts? Please click here to subscribe to our mailing list if you have not already. We only email post updates. You can also follow us on twitter at @webrtcHacks for blog updates and news of technical WebRTC topics or our individual feeds @chadwallacehart@reidstidolph, @victorpascual and @tsahil.

The post The WebRTC Troubleshooter: appeared first on webrtcHacks.

3CX è sponsor al Microsoft Ignite 2015!

Libera il VoIP - Thu, 04/16/2015 - 16:12

3CX è Silver Sponsor al Microsoft Ignite 2015, che si terrà a Chicago dal 4 all’8 Maggio.

Il focus principale del Microsoft Ignite di quest’anno è la tecnologia Cloud, la Unified Communication e la Mobilità: in pratica è su misura per 3CX! Addetti ai lavori, esperti e opinion leaders parteciperanno all’evento, quindi iscrivetevi e partecipate ai lavori.

Durante tutti i giorni della conferenza verranno effettuate dimostrazioni live di 3CX Phone System e della nostra soluzione integrata di webconference, 3CX WebMeeting, basata su tecnologia WebRTC.

Venite ad incontrare il team 3CX USA e il CEO di 3CX Nick Galea allo stand #307

Per evitare contrattempi o sovrapposizioni, siete pregati di fissare un appuntamento via e-mail

Non vediamo l’ora di incontrarvi di persona al Microsoft Ignite 2015!

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Kamailio World 2015 – The Workshops

miconda - Wed, 04/15/2015 - 23:57
It is now about one month and a half till the start of Kamailio World Conference 2015. Continuing with the same event structure like in 2014, the afternoon of the first day, the 27th of May, is filled with several technical workshops. These sessions are intended to give a more hands-on perspective on the subjects, with deeper technical content.Last year, Sipwise showed how to deploy sip:provide CE – the open source out of the box IP Telephony Operator Platform – in a matter of minutes and customize it to fit better your needs. This year, Daniel Grotti, a long time SIP and Kamailio fellow, is going to show how to enable WebRTC for sip:provider CE in order to bridge the communication between the web world and the classic SIP phones. Few other typical use cases will be approached during the session.Carsten Bock, from NG Voice, is returning with another tutorial to show more of what can be done with Kamailio for IMS and VoLTE deployments. Besides the tutorial, the plan is to have a VoLTE testbed on site for the duration of the entire event, so the participants can test with their own devices.After presenting at the past editions the concept and the development of CGRateS, a carrier grade open source CDR rating engine, Dan Bogos is now coming with a hands-on session about how to integrate it with Kamailio for prepaid and postpaid billing.Ability to troubleshoot SIP routing and analyze the flows on the wire is one of the core elements required for VoIP engineers. Lorenzo Mangani, one of the co-founders of Homer SIP Capture project, is going to deliver a session on how to use existing open source tools (including Homer and sipgrep, but not limited to) to make the SIP troubleshooting process easier.All together are providing an amazing amount of knowledge from the people with first hand experience, those that built the systems. It is a unique opportunity at Kamailio World to get face to face to interact with such people.The content of conference days is filled with other very interesting sessions, including as well valuable technical details, presenting scalable and secure architectures or other products that can be used to complete the VoIP platforms with new features. Right now you can see details for a sections of presentations in the Schedule page.Be sure you don’t miss Kamailio World Conference 2015, during May 27-29, in Berlin, Germany – it is the open source real time communications event in Europe!Secure your participation and register now!See you in Berlin!

Put in a Bug in Apple’s Apple – Alex Gouaillard’s Plan

webrtchacks - Tue, 04/14/2015 - 13:08

Apple Feast photo courtesy of flikr user Overduebook. Licensed under Creative Commons NC2.0.

One of the biggest complaints about WebRTC is the lack of support for it inside Safari and iOS’s webview. Sure you can use a SDK or build your own native iOS app, but that is a lot of work compared to Android which has Chrome and WebRTC inside the native webview on Android 5 (Lollipop) today. Apple being Apple provides no external indications on what it plans to do with WebRTC. It is unlikely they will completely ignore a W3C standard, but who knows if iOS support is coming tomorrow or in 2 years.

Former guest webrtcHacks interviewee Alex Gouillard came to me with an idea a few months ago for helping to push Apple and get some visibility. The idea is simple – leverage Apple’s bug process to publicly demonstrate the desire for WebRTC support today, and hopefully get some kind of response from them. See below for details on Alex’s suggestion and some additional Q&A at the end.

Note: Alex is also involved in the webrtcinwebkit project – that is a separate project that is not directly related, although it shares the same goal of pushing Apple. Stay tuned for some coverage on that topic.

{“intro-by”: “chad“}

Plan to Get Apple to support WebRTC The situation

According to some polls, adding WebRTC support to Safari, especially on iOS and in native apps in iOS, is the most wanted WebRTC item today.

The technical side of the problem is simple: any native app has to follow Apple’s store rules to be accepted in the store. These rules state that any apps that “browse the web” need to use Apple provided WebView [rule 2.17] based on the WebKit framework. Safari is also based on WebKit. WebKit does not Support WebRTC… yet!

First Technical step

The project aims at addressing the technical problem within the first half of 2015. However, bringing WebRTC support to WebKit is just part of the overall problem. Only Apple can decide to use it in their products, and they are not commenting about products that have not been released.

There have been lots of signs though that Apple is not opposed to WebRTC in WebKit/Safari.

  • Before the Chrome fork of WebKit/WebCore in what became known as blink, Apple was publicly working on parts of the WebRTC implementation (source)
  • Two umbrella bugs to accept implementation of WebRTC in WebKit are still open and active in WebKit’s bugzilla, with an Apple media engineer in charge (Bug 124288 &  Bug 121101)
  • Apple Engineers, not the usual Apple standard representative, joined the W3C WebRTC working group early 2014 (public list), and participated to the technical plenary meeting in November 2014 (w3c members restricted link)
  • Finally, an early implementation of Media Streams and GetUserMedia API in WebKit was contributed late 2014 (original bug & commit).

So how to let Apple know you want it and soon – potentially this year?

Let Apple know!

Chrome and Internet Explorer (IE), for example, have set up pages for web developers to directly give their feedback about which feature they want to see next (WebRTC related items generally rank high by the way).  There is no such thing yet for Apple’s product.

The only way to formally provide feedback to Apple is through the bug process. One needs to have or create a developer account, and open a bug to let Apple know they want something.  Free accounts are available, so there is no financial cost associated with the process. One can open a bug in any given category, the bugs are then triaged and will end up in “WebRTC” placeholder internally.

Volume counts. The more people will ask for this feature, the most likely Apple is to support it. The more requests the better.

But that is not the only thing that counts. Users of WebRTC libraries, or any third party who has a business depending on WebRTC can also raise their case with Apple that their business would profit from Apple supporting WebRTC in their product. Here too, volume (of business) counts.

As new releases of Safari are usually made with new releases of the OS, and generally in or around September, it is very unlikely to see WebRTC in Safari (if ever) before the next release, late 2015.

We need you

You want WebRTC support on iOS? You can help. See below for a step-by-step guide on how.

How to Guide Step-by-step guide
  1. Register a free Apple Developer account. Whether you are a developer or not does not matter eventually. You will need to make an Apple ID if you do not have one already.
  2. Sign in to the Bug Reporter:
  3. Once signed in, you should see the following screen:
  4. Click on Open, then select Safari:
  5. Go ahead and write the bug report:

It is very important here that you write WHY, in your own words, you want WebRTC support in Safari. There are a multiple of different reasons you might want it:

  • You’re a developer  you have developed a website that requires WebRTC support, and you cannot use it on Safari. If your users are requesting it, please share the volume of request, and/or share the volume of usage you’re getting on non-safari browsers to show the importance of the this for Apple.
  • You’re a company with a WebRTC product or service. You have the same problem as above, and the same suggestions apply.
  • You’re a user of a website that requires WebRTC, and owner of many Apple devices. You would love to be able to use your favorite WebRTC product or service on your beloved device.
  • You’re a company that propose a plugin for WebRTC in Safari, and you would love to get rid of it.
  • others

Often times, some communities organize “bug writing campaigns” that include boilerplate text to include in a bug.  It’s a natural tendency for reviewers to discount those bugs somewhat because they feel like more of a “me too” than a bug filed by someone that took 60 seconds to write up a report in their own words.

{“author”, “Alex Gouaillard“}

{“editor”, “chad“}

Chad’s follow-up Q&A with Alex

Chad: What is Apple’s typical response to these bug filing campaigns?

Alex: I do not have the direct answer to this, and I guess only Apple has. However, here are two very clear comments by an Apple representative:

The only way to let Apple know that a feature is needed is through bug filling.

I would just encourage people to describe why WebRTC (or any feature) is important to them in their own words. People sometimes start “bug writing campaigns” that include boilerplate text to include in a bug, and I think people here have a natural tendency to discount those bugs somewhat because they feel like more of a “me too” than a bug filed by someone that took 60 seconds to write up a report in their own words.”

So my initiative here is not to start a bug campaign per say, where everybody would copy paste the same text, or click the same report to increment a counter. My goal here is to let the community know they can let Apple know their opinion in a way that counts.

[Editor’s note: I was not able to get a direct confirmation from Apple (big suprise) – I did directly confirm  evidence that at least one relevant Apple employee agrees with the sentiment above.]

Chad: Do you have any examples of where this process has worked in the past to add a whole new W3C-defined capability like WebRTC?

Alex: I do not. However, the comment #1 above by Apple representative was very clear that whether it will eventually work or not, there is no other way.

Chad: Is there any kind of threshold on the number of bug filings you think the community needs to meet?

Alex: My understanding is that it’s not so much about the number of people that send bugs, it’s more about the case they make. It’s a blend between business opportunities and number of people. I guess volume counts – whether it is people or dollars. This is why it is so important that people use they own words and describe their own case. 

Let’s say my friends at various other WebRTC Platform-as-a-Service providers desire to show the importance for them of having WebRTC in iOS or Safari- one representative of the company could go in and explain their use case and their numbers for the platform / service. They could also ask their devs to file a bug describing their application they developed on top of their WebRTC platform. They could also ask their users to describe why as users of the WebRTC app that they feel segregated against their friends who owns a Samsung tablet and who can enjoy WebRTC while they cannot on their iPad. (That is just an example, and I do not suggest that they should write exactly this. Again, everybody should use their own word.)

If I understand correctly, it does not matter whether one or several employees of the above named company fill only one or several bugs for the same company use case.

Chad: Are you confident this will be a good use of the WebRTC developer’s community’s time?

Alex: Ha ha. Well, let’s put it that way, the whole process takes around a couple of minutes in general, and maybe just a little bit more for companies that have a bigger use case and want to weight in the balance. Less than what you are spending reading this blog post. If you don’t have a couple of minute to fill a bug to Apple, then I guess you don’t really need the feature.

More seriously, I have been contacted by enough people that just wanted to have a way, anyway, to make it happen, that I know this information will be useful. For the cynics out there, I’m tempted to say, worse case scenario you lost a couple of minutes to prove me wrong. Don’t miss the opportunity.

Yes, I’m positive this will be a good use of everybody’s time.

{“interviewer”, “chad“}

{“interviewee”, “Alex Gouaillard“}

Want to keep up on our latest posts? Please click here to subscribe to our mailing list if you have not already. We only email post updates. You can also follow us on twitter at @webrtcHacks for blog updates and news of technical WebRTC topics or our individual feeds @chadwallacehart@reidstidolph, @victorpascual and @tsahil.

The post Put in a Bug in Apple’s Apple – Alex Gouaillard’s Plan appeared first on webrtcHacks.

Testing FreeSWITCH performance on Scaleway C1

TXLAB - Sat, 04/11/2015 - 02:23

The dedicated ARM hosting servers at Scaleway appear to be a decent platform for a mid-sized PBX.

In short, the platform displays the following results in performance tests:

  • OPUS<->PCMA transcoding: 16 simultaneous calls with  at about 95% total CPU load and no noticeable distortions.
  • SILK<->PCMA transcoding: 72 simultaneous calls were going without distortions, with average total CPU load at 63%. Higher number of calls resulted in noticeable distortions.
  • G722<->PCMA transcoding: 96 simultaneous calls without distortions, at 76% CPU load, and noticeable distortions for higher numbers.

Test 1: sequential transcoding

The following tests are a slight modification of my previous test scenario: it appears that a channel in OPUS codec cannot execute `echo` or `delay_echo` FreeSWITCH applications, as they copy RTP frames, and the OPUS codec is stateful and does not accept such copying. So, an extra bridge is made to ensure that echo is always executed on a PCMA channel.

XML dialplan in public context (here IPADDR is the public address on the Scaleway host):

  <!-- Extension 100 accepts the initial call, plays echo,        and on pressing *1 it transfers to 101  -->   <extension name="100">     <condition field="destination_number" expression="^100$">       <action application="answer"/>       <action application="bind_meta_app" data="1 a si transfer::101 XML ${context}"/>       <action application="delay_echo" data="1000"/>     </condition>   </extension>       <!-- Extension 101 plays a beep, then makes an outgoing SIP call to        our own external profile and extension 200  -->   <extension name="101">     <condition field="destination_number" expression="^101$">       <action application="playback" data="tone_stream://%(100,100,1400,2060,2450,2600)"/>       <action application="unbind_meta_app" data=""/>       <action application="bridge"               data="{absolute_codec_string=PCMA}sofia/external/200@IPADDR:5080"/>     </condition>   </extension>   <!-- Extension 200 enforces transcoding and sends the call to 201 -->   <extension name="200">     <condition field="destination_number" expression="^200$">       <action application="answer"/>       <action application="bridge"               data="{max_forwards=65}{absolute_codec_string=OPUS}sofia/external/201@IPADDR:5080"/>     </condition>   </extension>       <!-- Extension 201 returns the call to 100, guaranteeing it to be in PCMA -->   <extension name="201">     <condition field="destination_number" expression="^201$">       <action application="answer"/>       <action application="bridge"               data="{max_forwards=65}{absolute_codec_string=PCMA}sofia/external/100@IPADDR:5080"/>     </condition>   </extension>

The initial call is sent to extension 100 in the public context, and then by pressing *1, 6 additional channels are created, of which two calls perform the transcoding from PCMA to OPUS and back. So, if “show channels” shows 43 total channels, it corresponds to 42 = 6*7 test channels plus the incoming one, or 14 transcoding calls.

#### Good quality #### # fs_cli -x 'show channels' | grep total 43 total. # mpstat -P ALL 10                       Linux 3.19.3-192 (scw01)    04/10/2015      _armv7l_        (4 CPU) 10:08:41 PM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle 10:08:51 PM  all   82.67    0.00    2.75    0.00    0.00    1.30    0.00    0.00   13.28 10:08:51 PM    0   92.80    0.00    1.30    0.00    0.00    5.20    0.00    0.00    0.70 10:08:51 PM    1   95.30    0.00    1.60    0.00    0.00    0.00    0.00    0.00    3.10 10:08:51 PM    2   89.90    0.00    2.50    0.00    0.00    0.00    0.00    0.00    7.60 10:08:51 PM    3   52.70    0.00    5.60    0.00    0.00    0.00    0.00    0.00   41.70 10:08:51 PM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle 10:09:01 PM  all   84.88    0.00    2.43    0.00    0.00    1.23    0.00    0.00   11.47 10:09:01 PM    0   94.50    0.00    0.50    0.00    0.00    4.90    0.00    0.00    0.10 10:09:01 PM    1   97.60    0.00    1.50    0.00    0.00    0.00    0.00    0.00    0.90 10:09:01 PM    2   87.70    0.00    2.20    0.00    0.00    0.00    0.00    0.00   10.10 10:09:01 PM    3   59.70    0.00    5.50    0.00    0.00    0.00    0.00    0.00   34.80 #### quite OK quality, with some minor distortions #### # fs_cli -x 'show channels' | grep total 49 total. # mpstat -P ALL 10                       Linux 3.19.3-192 (scw01)    04/10/2015      _armv7l_        (4 CPU) 10:10:29 PM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle 10:10:39 PM  all   95.65    0.00    2.40    0.00    0.00    0.83    0.00    0.00    1.12 10:10:39 PM    0   95.30    0.00    1.20    0.00    0.00    3.30    0.00    0.00    0.20 10:10:39 PM    1   96.90    0.00    2.20    0.00    0.00    0.00    0.00    0.00    0.90 10:10:39 PM    2   95.80    0.00    3.50    0.00    0.00    0.00    0.00    0.00    0.70 10:10:39 PM    3   94.60    0.00    2.70    0.00    0.00    0.00    0.00    0.00    2.70 10:10:39 PM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle 10:10:49 PM  all   91.55    0.00    1.55    0.00    0.00    0.78    0.00    0.00    6.12 10:10:49 PM    0   89.90    0.00    1.20    0.00    0.00    3.10    0.00    0.00    5.80 10:10:49 PM    1   96.60    0.00    0.70    0.00    0.00    0.00    0.00    0.00    2.70 10:10:49 PM    2   90.60    0.00    1.70    0.00    0.00    0.00    0.00    0.00    7.70 10:10:49 PM    3   89.10    0.00    2.60    0.00    0.00    0.00    0.00    0.00    8.30 #### bad quality, barely audible #### # fs_cli -x 'show channels' | grep total 55 total.

If OPUS codec is replaced with SILK in the above configuration, the test is not usable, as SILK appears not to tolerate multiple transcodings, and after 4 transcodings the sound is almost not propagated at all. Also further transcoding sessions treat the input as silence, and do not load CPU.

If G722 is used, 36 transcoded calls still leave plenty of CPU resources for other tasks:

# fs_cli -x 'show channels' | grep total 109 total. # mpstat -P ALL 10                       Linux 3.19.3-192 (scw01)    04/10/2015      _armv7l_        (4 CPU) 10:37:31 PM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle 10:37:41 PM  all   19.75    0.00    5.40    0.00    0.00    0.00    0.00    0.00   74.85 10:37:41 PM    0   27.00    0.00   12.10    0.00    0.00    0.00    0.00    0.00   60.90 10:37:41 PM    1    4.30    0.00    9.50    0.00    0.00    0.00    0.00    0.00   86.20 10:37:41 PM    2   47.60    0.00    0.00    0.00    0.00    0.00    0.00    0.00   52.40 10:37:41 PM    3    0.10    0.00    0.00    0.00    0.00    0.00    0.00    0.00   99.90 10:37:41 PM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle 10:37:51 PM  all   17.57    0.00    7.42    0.00    0.00    0.00    0.00    0.00   75.00 10:37:51 PM    0    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00 10:37:51 PM    1   20.30    0.00   29.70    0.00    0.00    0.00    0.00    0.00   50.00 10:37:51 PM    2   50.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00   50.00 10:37:51 PM    3    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00  Test 2: parallel transcoding

The following piece of public dialplan takes the call at extension 300, makes a call in OPUS to extension 301, and then the call is bridged to 302 in PCMA where a speech test file is played endlessly. Thus, a call to 300 produces 5 channels, which are equivalent of two transcoded calls.

  <extension name="300">     <condition field="destination_number" expression="^300$">       <action application="answer"/>       <action application="bridge"               data="{absolute_codec_string=OPUS}sofia/external/301@IPADDR:5080"/>     </condition>   </extension>       <extension name="301">     <condition field="destination_number" expression="^301$">       <action application="answer"/>       <action application="bridge"               data="{absolute_codec_string=PCMA}sofia/external/302@IPADDR:5080"/>     </condition>   </extension>       <extension name="302">     <condition field="destination_number" expression="^302$">       <action application="answer"/>       <action application="endless_playback" data="/var/tmp/t02.wav"/>     </condition>   </extension>

In parallel to a call to 300 from outside, additional endless calls were produced from fs_cli:

originate sofia/external/300@IPADDR:5080 &endless_playback(/var/tmp/t02.wav)

This originate command produced 6 new channels, equivalent to two transcoded calls. The command was repeated until the human caller hears any distortions.

OPUS transcoding was functioning fine with 16 transcoded calls and 95% average CPU load, while SILK and G722 started showing distortions at around 65-75% of CPU load.



Filed under: Networking Tagged: arm, freeswitch, pbx, scaleway, voip

From SQL Tables to Kamailio Hash Tables

miconda - Thu, 04/09/2015 - 23:55
Eloy Coto Pereiro has published recently another blog post that can be useful in the case one needs to cache content of custom database tables in Kamailio’s memory via htable module. The article uses Postgresql as database server, but same mechanism can be used for other database servers.You can read the article at:Using caching is a good way to improve the performances and htable is a very flexible mechanism in Kamailio configuration file, with plenty of options to tune the caching rules.Enjoy!


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