7965 SIP firmware iLBC codec

Unanswered Question
Mar 23rd, 2009


Does any body know how to setup 7965 with SIP firmware to use iLBC 30ms frame. Something like IOS dial-peer command "codec ilbc mode 30"

I have media gateway that supports only 30ms frame, phone works 50% of them with it. I could hear the normal audio sometimes, but in most cases it's broken and wolfs wail.

I have this problem too.
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Paolo Bevilacqua Mon, 03/23/2009 - 10:41

You might find that it is not possible at all.

Cisco develops SIP firmware only for use by CM and CME platforms, if these are not going to use certain features,or use it in a non-standard way, you're pretty much stuck.

Nicholas Matthews Mon, 03/23/2009 - 20:06

I do not believe that the 7965 supports iLBC, even with SCCP. The phones will support G.711, G.729, and G.722 to my knowledge, and any other codecs must be transcoded.



Nicholas Matthews Mon, 03/23/2009 - 20:17

Ah ok, I see they added iLBC along with G.722. Did not know.

I haven't seen anyone try this yet :)

Good luck with the packetization rate, I wouldn't be surprised to find that the phone only supports the most common, whichever that is.


klondike@ameri-... Mon, 03/23/2009 - 20:25


The phone supports both. BUT! Is there a way to set firm the packetization to 30ms.

Like any IOS based Cisco router????

Nicholas Matthews Mon, 03/23/2009 - 20:47

Technically - the packetization rate should be set by the call agent via media negotiation.

Do the phones send early media for outgoing calls with 3rd party agents? If so, do they just advertise everything?

Doing a little digging - these are actually not designed with 3rd party control like the 7940's and 7960's. They aren't a TAC supported solution, which means a TAC case wouldn't get you very far either.

To troubleshoot this, I would do a pretty deep inspection of the SDPs exchanged with CME in this case, as well as the .cnf file downloaded from CME when it registers.

Best of luck :)



klondike@ameri-... Mon, 03/23/2009 - 20:16

Hi Nick,

Yes, they DO support iLBC with both packetization settings. The problem is impossible (so far) to set framing either 20ms or 30 ms. The phone tries to play smart as$ switching from 20ms to 30ms randomly, which causes the wolfs wail...



P.S. I have perfectly working CME 7.1 setup with transcoders on CME to support iLBC on the SIP trunk to provider and SCCP 711 inside on the LAN. Now I need make working stand alone 7965 with SIP firmware in it with 30ms frame....


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