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g729a codec problem bet. Asterisk and Cisco AS5300

Hi,

We have an audio codec problem in our calls involving our telephony system and our providers Cisco AS5300 trunk.

Our telephony system is Asterisk version 1.6.2.14 . G729a Codec is licensed, bought from Digium.

AS5300 trunk is our outgoing calls sip peer.

We set the sip peer to allow only g729. The call attempt is able to connect, but when answered, no audio is heard or transmitted.

We can hear audio only when we both allow ulaw codec.

We do not have this problem on our other providers using asterisk and other non-cisco systems.

Anyone else having this same problem?

Here's our config (both sides) and the sip debug output:

Asterisk sip.conf setting:

type=peer

disallow=all

allow=g729

host=xxx.xxx.xxx.xxx

fromdomain=xxx.xxx.xxx.xxx

dtmfmode=rfc2833

nat=no

canreinvite=yes

context=from-trunk-sip-iaccess

AS5300 Settings:

codec preference 1 g729r8

codec preference 2 g729br8

codec preference 3 g723r53

codec preference 4 g723r63

codec preference 5 g723ar53

codec preference 6 g723ar63

SIP Debug Output:

v=0

o=root 1686167830 1686167830 IN IP4 yyy.yy.yy.yy

s=Asterisk PBX 1.6.2.14

c=IN IP4 yyy.yy.yy.yy

t=0 0

m=audio 14212 RTP/AVP 18 0 8 3 101

a=rtpmap:18 G729/8000

a=fmtp:18 annexb=no

a=rtpmap:0 PCMU/8000

a=rtpmap:8 PCMA/8000

a=rtpmap:3 GSM/8000

a=rtpmap:101 telephone-event/8000

a=fmtp:101 0-16

a=ptime:20

a=sendrecv

v=0

o=CiscoSystemsSIP-GW-UserAgent 6911 3862 IN IP4 xxx.xxx.xxx.xxx

s=SIP Call

c=IN IP4 xxx.xxx.xxx.xxx

t=0 0

m=audio 18132 RTP/AVP 18

c=IN IP4 xxx.xxx.xxx.xxx

a=rtpmap:18 G729/8000

a=fmtp:18 annexb=no

a=ptime:20

Everyone's tags (4)
1 REPLY

Re: g729a codec problem bet. Asterisk and Cisco AS5300

hi Karlo,

To do this you need to specify which variant to use (G.729 or G.729A) this is related to

the codec complexity configuration on the voice card. It does not show up explicitly in

the Cisco IOS command line interface (CLI) codec choice. For example, the CLI does not

show g729ar8 ("a" code) as a codec option. However, if the voice-card is defined as

medium-complexity, then the g729r8 option is the G.729A codec.

Therefore configure "g729r8" as this will be G729a (medium complexity) as long as

the voice-card is setup for medium complexity. If however you can't change this or don't

get the option its assumed that there are enough DSPs to support all calls as high

complexity.

You can check these two documents for the configuration:

http://www.cisco.com/en/US/partner/products/hw/gatecont/ps2250/products_tech_note09186a008011537d.shtml

http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120limit/120xh/puccini.htm

Hope this helps!

Thanks,

Karthik

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