[SIPForum-discussion] Transcoding devices in VOIP

Aniella Juverdeanu Aniella.Juverdeanu at telus.com
Mon Jul 11 16:06:43 UTC 2011


It is not an easy task to accomplish. The media parameter negotiation is important and generates extra signaling during call setup (mostly if you have a mobile softswitch or for features as call forwarding, call transfer, etc.). The best cost effective and quality wise is to have media end points to support a variety of CODEC types - and this seems to become more and more a norm.
We planned on using a Transcoding platform but comes at high price and it is a lot to test when you have carrier and other types of applications in the network. We found Audiocodes a good solution. To save on capacity and money spent you can have the SBC forward to this transcoding device only on rejection from the far end (i.e. SIP 488 - although not always 488 is used for CODEC mismatch) or configure the SBC to check the CODEC list in SDP and forward to the transcoding device if the specific CODEC is not on the list. But it still looked expensive to test and implement.
It looks like a majority of carriers don't do it as they asked to us to support. Other carriers require a SIP 488 release form us to re-route specific CODEC type calls.
No - didn't use CUBE for it.
CPU usage for transcoding should be specific to the vendor of the box. Bandwidth should be according to the codec types on each side of the transcoding device. Cannot be less or more than the CODEC used.

From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of amit salunkhe
Sent: July 10, 2011 12:33 PM
To: discussion at sipforum.org
Subject: [SIPForum-discussion] Transcoding devices in VOIP

Dear All

1.How msuch possible and correct to do trasncoding in VOIP carriere level platforms?
2 .Any carrier doing transcoding in VOIP world?
3. Other than SBc whcih are teh seperate platform we can sue for transocindg? any well known?
4.If i wish to do trasncoding on seperate BOX (out of my SBC) is the same call flow of media packets? or signaling packets to do transcoding?

A Party-------->SBC--------------->Tarnscoder BOX------------>SBC(Same)--------------->B Part or far end?

5. have anybody using Csico CUBE for Transcoding?
6. based on diffrent codec types and annex CPU usage and bandwidth consumption is diffrent while transcondng?

Thanks & Regards
Amit Salunkhe

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