call manager and codec selection granularity

Unanswered Question
Nov 15th, 2006
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Dear all, please advice


I have Call Manager Express that currently

accepts calls from ip-phones for 2 (two) different

patterns: 3T and 4T. It then directs these calls to

the h323-gateway [] using:

* g711 codec for 3T


* g729 codec for 4T.

It works fine!

Call Manager Express cutted config:


dial-peer voice 10 voip

destination-pattern 3T

codec g711ulaw bytes 240

session target ipv4:


dial-peer voice 20 voip

destination-pattern 4T

codec g729br8 bytes 40

session target ipv4:


I've got also Call Manager 4.1 and a strong wish to implement

abovementioned model using not express version.

The question is it possible in principle ?

If yes, could you please describe how ?

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Overall Rating: 2 (1 ratings)
Chris Deren Wed, 11/15/2006 - 10:01
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    2017 IP Telephony, Contact Center, Unified Communications

First of all let me ask you what would be the reason to have seperate dial-peers to point to the same destination using different codecs?

With H323 GW you should be able to accomplish this the same way, bascially have route patterns 4! and 3! pointing to the same GW, and the same dial-peers, keep in mind then when you create a GW in CCM you assign Device Pool which references Region which in fact controls what codec is allowed, so make sure the Region used by this GW is set to use G711 between other regions, which will allow for negotiation of both G711 and G729.

HTH, please rate all posts!


Tobivan_Helden_2 Thu, 11/16/2006 - 07:26
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- The reason to have separate dial-peers to point to the same destination are:

* routing process is based on h323 proxy logic

* h323 proxy then route 3T (in g711) to -A- voip provider that _has_ possibility to accept calls in g711

* h323 proxy on the other hand route 4T (in g729) to -B- provider that _cannot_ accept g711, only g729 (!)

- Then using CCM Administration interface:

a. i've created REGION_PHONE, assigned it to device pool DP_PHONE, then inserted my ip-phone into pool DP_PHONE

b. i've created REGION_PROXY, assigned it to device pool DP_PROXY, then inserted my proxy into pool DP_PROXY

c. i've defined, that codec, that is used for calls between REGION_PHONE & REGION_PROXY, will be g711

- And get the following:

a. i've dialed from my ip-phone 3T and call is routed to Route List, that contains my proxy. Call is established successfully using g711 codec and that was really predictable!

b. i've dialed from my ip-phone 4T and call is also routed to Route List, that contains my proxy. Call is not

established due to h.245 capabilities won't be negotiated (my proxy can g711 while h323 gateway of provider -B-

can only g.729 as i mentioned earlier)

So that's the problem in my opinion!

Thank you.

Tobivan_Helden_2 Tue, 11/21/2006 - 01:18
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Might it be that my request hasn't been clearly described ?

Please, advice something. Maybe it will be possible through using transcoding ?

Thank you,

With Hope for your help

msolak Fri, 11/24/2006 - 08:30
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the problem is you have one h323-gateway with two type of codecs. you can configure only one h323-gateway with the same ip adress.

following setup could be the solution for your outgoing calls:

1. configure the lmhosts file with different names for your gateways on your CCM:






REGION-PROXY-A (G711)-> DP-PROXY-A, h323-gateway-proxy-a


REGION-PROXY-B (G7729)-> DP-PROXY-B, h323-gateway-proxy-b

5. Route Pattern 3! --> h323-gateway-proxy-a

Route Pattern 4! --> h323-gateway-proxy-b




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