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New Member

VoIP/P1 - G.729 & co : A few of easy questions to answer...

Hello everybody!

I just want to make clear or confirm something I hope being the way I suppose it is...Here we go:


I suppose that G.729r8 is default codec for VoIP on C1700 platform (it doesn't appear in config after typing). Is it true?

I'm just asking because there is no explicit notice of this in :


Having C1750-2V, 2FXS card, and G.729r8 as default codec, when I type 'show voice dsp', it lists two voice channels possible to process at once by the DSP chip. That's okay. But why there is a 'g711ulaw' codec shown ???

It doesn't change with either codec configuring..


Having the same hardware, theory in document :

and knowledge, that 'codec complexity' comm. doesn't exist on IOS for C1700 - I want to know, why after configuring G.729 Annex-A codec with 'codec g729ar8' or 'codec g729abr8' the router doesn't provide with possibility of 4 simult. calls ???

Generally, with G.729r8 as high-complexity codec a 'show voice dsp' shows properly 2 channels allocated (or possible to process). But with Annex-A as medium-complex codec there should really be the appropriate offer. Also 'show diag' gives info that this better C549 DSP chip is used...

Perhaps silly question - with G.729ar8 configured, will this info (and real DSP support) from 'show voice dsp' change to 4 channels allocated if I insert another 2FXS card??


Just to confirm - after typing 'show voice call', the phone numbers for existing voice ports are probably the last numbers to be actively used on them. Is that true?


Theoretically having C1751, 2x 2BRI-NT/TE card and PVDM-256-12K installed, is it possible to run properly at least one port of the second card while there is no full DSP support for them (espec. for high-complexity codecs) ???

It's clear, thar 8K covers first card, and the other one is covered by left 4K somehow from the half..

That's all, friends. Thanks you in advance for your answers.


Re: VoIP/P1 - G.729 & co : A few of easy questions to answer...

Since there has been no response to your post, it appears to be either too complex or too rare an issue for other forum members to assist you, or there is no public information available at this time. If you don't get a suitable response to your post, you may wish to review our resources at the online You may also contact our product information line at 1-800-553-NETS or a Cisco Systems Engineer at your local Cisco office or reseller. To locate your local Cisco representative, visit

If anyone else in the forum has some advice, please reply to this thread.

Thank you for posting.

New Member

Re: VoIP/P1 - G.729 & co : A few of easy questions to answer...

Hmmm, nobody was ABLE...

I think this isn't place of -many- helping people, if yes (you get the answer) - then this probably due to positive star constellation.. :-/