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Results: Free Software voice & video testing

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Last weekend on Software Freedom Day the Manchester FSFE Fellowship group, assisted by additional participants in Britain and Germany, spent the afternoon testing Free Software alternatives to Skype.

Results

The 25 sets of results were recorded, and can be browsed, sorted, and searched below.

Six audio tests successfully passed (24%), as did five video tests (20%). Mumble was the most successful client, passing 100% of tests (audio only, video is not yet supported). XMPP passed four out of 14 audio tests, whereas SIP passed only one out of ten (both video and audio). Of nine apps tested, only Mumble, Pidgin, Jitsi, and Google Talk's web client achieved passes.

Conclusions

The clients tested performed more poorly than expected, probably due to network problems. One of the difficulties in testing was that generally there was little or no information about why the test had failed.

SIP clients couldn't connect successfully except when both testers used the same client, and had accounts on the same SIP server. This was surprising, especially considering that the accounts used for testing were is many cases paid for and commercially supported.

The only client and protocol which consistently did what it promised was Mumble, which had 100% test pass rate. Unlike all other clients, Mumble uses its own protocol, and also offers audio conferencing and text-to-speech by default. Mumble users are constrained to using the same server however, unlike SIP and XMPP users who should theoretically each be able to use a separate server of their choice.

It would have been useful to have a local SIP and XMPP server on the same network as the testers in order to better identify network related problems. This could have helped determine whether failures stemmed from the client, network, or server..

Examining STUN and ICE configurations was beyond the scope of our tests, but as these technologies seem critical to whether calls succeed or fail, they merit careful examination when choosing or configuring SIP and XMPP servers.

FSFE Fellows will be pleased to note that XMPP calls using FSFE's own XMPP server were often successful: several volunteers could see and hear each other when both were using their @jabber.fsfe.org accounts.

A Skype alternative?

Skype uses a variety of notorious methods to punch through network obstacles like firewalls, and to ensure it can locate the intended call recipient wherever they may be. It also benefits from being a centralised system where, if necessary, all roads lead to Rome (or a Skype managed server, at least).

Contrastingly, Free Software systems play by conventional rules of network traffic, and try and connect callers using established procedures. They also have to communicate with a variety of different servers, which may operate in ways they don't know or expect. In addition to this, some of the chat clients that we tested have only recently added support for more than text-based chatting (Gajim in Debian testing is too old for video, for example), and probably add a few problems of their own into the mix.

Based on our test results, those looking for a Free Software Skype alternative should use either Mumble, or SIP with all callers on the same server and using the same client.

Moving Forward

We had hoped to publish a conclusive compatibility table of chat clients, providing a reference for people needing to know "what works with what", and "what is easiest". Instead, we have table of subjective results, and a list of questions:

If you have answers to these questions, please share them in the comments of the blog edition of this article.

Table

More data is available in the table source code.

From ClientFrom OSFrom DETo ClientTo OSTo DEReportLocaltypeAudioVideoNotesAccount 1Account 2
Pidgin 2.7.3CrunchbangopenboxPidgin 2.1Fedora 17GnomeAnnatrueXMPPpasspass
Pidgin 2.7.3Crunchbangopenboxgajim 0.15Fedora 17GnomeAnnatrueXMPPfailpass
Jitsi 1.0-build.3967Ubuntu 12.04Gnome/UnityGajim 0.15Fedora 17GnomeJamietrueXMPPfailfailOptions were greyed out on Gajim
Pidgin 2.10.6Ms Win XPnaPidgin 2.7.3crunchbang openboxDavidfalseXMPPfailfail
Empathy 3.4.2.3Fedora 17GnomeEmpathy 3.4.2.3Ubuntu 12.04Gnome/UnitySamtrueXMPPfailfailonly text chat worked - no indication of a call request was received for either video or voice calls
snom220 hardphone snom220-SIP 3.56zSnom LinuxNA WookeyfalseSIPfailfailcall connection failed: 'No such domain' - local DNS failure3858102@SIPgate.co.ukwellybob@jabber.me
snom220 hardphone snom220-SIP 3.56zSnom LinuxNA wookeyfalseSIPfailfailcall connection failed: 'No such domain' - local DNS failure3858102@SIPgate.co.uksamtuke@SIP.linphone.org
snom220 hardphone snom220-SIP 3.56zSnom LinuxNAn900 appMaemo 5hildonwookeyfalseSIPfailfailcall connection failed: 'No such domain' - local DNS failure3858102@SIPgate.co.uk2542654@localphone.com
n900 21.2011.38-1Maemo 5HildonlinphonewookeyfalseSIPfailfailcall connection failed: 'unable to call, contact offline9178850@SIPgate.co.uksamtuke@SIP.linphone.org
n900 21.2011.38-1Maemo 5Hildonn900 appMaemo 5hildonwookeyfalseSIPfailfailcall connection failed: 'unable to call, contact offline9178850@SIPgate.co.uk
n900 21.2011.38-1Maemo 5Hildonsnom220 hardphone snom220-SIP 3.56zSnom LinuxNASamfalseSIPfailfailcall connection failed: no response" 1st time, call unauthorised 2nd time"samtuke@SIP.linphone.org | 2542654@localphone.com
n900 21.2011.38-1Maemo 5Hildonn900 21.2011.38-1Maemo 5HildonSamfalseSIPfailfailcall connection failedsamtuke@SIP.linphone.org | 2542654@localphone.com3858102@SIPgate.co.uk
Jitsi 1.0-build.3967Ubuntu 12.04Gnome/UnityJitsi 1Fedora 17GnomeJamietrueXMPPfailfailICE failed9178850@SIPgate.co.uk
Pidgin unknownUbuntu 12.04Gnome/UnityPidgin 2.1Fedora 17GnomeJamietrueXMPPfailfailICE failed
mumble 1.2.3Fedora 17GnomeMurmur murmur-static_x86-1.2.3-412Debian WheezySamfalsemumblepassnausing bens server, it just works
Pidgin 2.7.3Crunchbangopenboxkopete 1.2.5Fedora 17GnomeAnnatrueXMPPfailfailkopete couldn't initiate call with pidigin, only pidgin could initiate with kopete
Kopete 1.0.0CrunchbangopenboxPidgin 2.1Fedora 17GnomeAnnatrueXMPPfailfail
Jitsi 1.0-build.3967OSX 10.6.8NAPidgin? ?UbuntuKDERobinfalseXMPPpasspassnotes
Jitsi 1.0-build.3967OSX 10.6.8NAJitsi 1.0-build.3967FedoraGnomeRobintrueSIPpasspassAudio one one was pretty garbled, both using SIP2SIP
Jitsi 1.0-build.3967OSX 10.6.8NAJitsi 1.0-build.3967FedoraGnomeRobintrueSIPfailfailfailed using different servers: SIP2SIP and localphone
linphone 3.5.2Fedora 17GnomeJitsi 1.0-build.3967OSX 10.6.8NASamtrueSIPfailfailfailed using different servers: SIP2SIP and linphone
Pidgin 2.10.3Kubuntu 12.04KDEGoogle Talk, webclient ???OSX, AndroidNASteffitrueXMPPpasspass
Pidgin 2.10.3Kubuntu 12.04KDEGoogle Talk, webclient ??????NASteffifalseXMPPpassfailVideo was fine, audio worked but the quality was very low
Psi 0.14Fedora 17Gnomepsi+ 0.15.5337OSXNASamtrueXMPPfailfail
Psi/Psi+ v0.15.5339-webkitFedora 17Gnomepsi+ Psi+ v0.15.3910KKubuntu 12.04KDESamtrueXMPPfailfailauth requests never appeared, voice chat enabled via pssimedia client