Carla, There can be both performance and licensing issues. G.729a is the most widely used high quality compressed codecs, but you needs to buy licenses from Digium...$10 per stream. Digium provides this as a service, passing the license fees on to the patent holder.
It's CPU intensive so a Soekris Net4801 will only encode/decode two calls using G.729a. I presently run Astlinux on a H-P T5700 thin client with a 1 GHz CPU. It can transcode 5-6 calls. See voip-info.org for "system dimensioning" to see details on larger systems. There are DSP cards that can add to suitable hosts to move the transcoding activity off the host CPU. These are good but costly solutions. As a practical matter if you're dealing with known ITSPs or peers then you should be able to limit the codecs required and G.729s may not be an issue. In fact ILBC may not be an issue. G.711a/u and GSM get it done for a lot of providers. Michael On Tue, 5 Dec 2006 22:40:40 -0800, Carla Schroder wrote: >Gah, so it depends on whatever the people calling my network are using? Is >there any downside to allowing all codecs, like performance issues? Assume a >magical world with no licensing hassles for proprietary codecs. :) > >On Tuesday 05 December 2006 18:38, Michael Graves wrote: >> Carla, >> >> The system will offer to negotiate a connection with the allowed >> codecs. If it cannot then the call will simply be refused. You can >> allow GSM and ILBC as these are royalty free and commonly used. If you >> find that ILBC calls are poor quality you can always rem out that line >> later on. >> >> Noe also that you can specify the codecs in the general section and >> also on a per peer basis. >> >> Michael >> >> On Tue, 5 Dec 2006 18:02:24 -0800, Carla Schroder wrote: >> >hey all, >> > >> >How do you decide which codecs to allow in sip.conf? A typical >> > configuration looks like this: >> > >> >disallow=all >> >allow=alaw >> >allow=ulaw >> > >> >What happens when a call comes in that uses a different codec? Any >> > pointers to a good reference are welcome. >> > >> >-- > > >-- >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >Carla Schroder >Linux geek and random computer tamer >check out my Linux Cookbook! >http://www.oreilly.com/catalog/linuxckbk/ >best book for sysadmins and power users >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >_______________________________________________ >Astlinux-users mailing list >[email protected] >http://lists.kriscompanies.com/mailman/listinfo/astlinux-users > >Donations to support AstLinux are graciously accepted via PayPal to [EMAIL >PROTECTED] > > -- Michael Graves [EMAIL PROTECTED] Sr. Product Specialist www.pixelpower.com Pixel Power Inc. [EMAIL PROTECTED] o713-861-4005 o800-905-6412 c713-201-1262 skye mjgraves fwd 54245 _______________________________________________ Astlinux-users mailing list [email protected] http://lists.kriscompanies.com/mailman/listinfo/astlinux-users Donations to support AstLinux are graciously accepted via PayPal to [EMAIL PROTECTED]
