Cisco CUBE unable to send PCMU in SDP to telco

[ragz3000]

Hi my Cisco router 3900 always send PCMA in sdp but telco wants PCMU only.

CUCM -> CUBE trunk has MTP checked, but MTP is shutdown state. Does this matter?

voice class codec 2 (applied on the outgoing dial-peer to ITSP)
codec preference 1 g711ulaw
codec preference 2 g711alaw

dspfarm profile 200 transcode
description transcode profile 200
codec g729abr8
codec g729ar8
codec g711ulaw
codec g729r8
codec g711alaw
maximum sessions 4
associate application SCCP
!
dspfarm profile 100 conference
description conference profile 100
codec g729br8
codec g729r8
codec g729abr8
codec g729ar8
codec g711alaw
codec g711ulaw
maximum sessions 4
associate application SCCP

dspfarm profile 1 mtp
codec g711ulaw
codec pass-through
maximum sessions software 8
associate application SCCP
shutdown

SIP INVITE message snippet.

Session-Expires: 10800
Content-Type: application/sdp
Content-Disposition: session;handling=required
Content-Length: 238
v=0
o=CiscoSystemsSIP-GW-UserAgent 4311 4515 IN IP4 10.0.8.86
s=SIP Call
c=IN IP4 10.0.8.86
t=0 0
m=audio 25704 RTP/AVP 8 101
c=IN IP4 10.0.8.86
a=rtpmap:8 PCMA/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
a=ptime:20

[Mohammed al Baqari]

Two options:

Preferred:

- On CUBE have incoming dialpeer which match all calls going to this ITSP
(for example have them prefixed with 89 on CUCM then match all calls with
89 at beginning and strip it in CUBE)
- This dialpeer should have 711alaw only. This will force CUCM to use
g711alaw

Option #2:

- Remove codec-passthrough from mtp
- Bring it up to do codec transformation

[ragz3000]

Thank you for reply, you mean update as below for option 2?

dspfarm profile 1 mtp
codec g711ulaw
maximum sessions software 8
associate application SCCP
no shutdown

or Can I make CUCM delayed offer (i mean disable "early offer support for voice and video calls- Mandatory Insert MTP if needed" in SIP trunk profile)

[HARIS_HUSSAIN]

1) Disable the Codec from CUCM Service Parameters and try

*** Please rate helpful post; Mark "Accept as a Solution" if applicable

Thanks,
Haris

[Mohammed al Baqari]

@HARIS_HUSSAIN this is not practical to disable the codec from entire
cluster for one scenario. There are many options on CUCM itself which can
solve this instead of disabling ulaw entirely.

[ragz3000]

Agree, I wouldn't disable that entirely.

What debug commands to use to understand which voice codec it selects and sends in offer to telco?

[HARIS_HUSSAIN]

Thanks, Mohammed For highlighting same. Yes disabling it globally will have other implications.

@ragz3000. Make sure that the Call is hitting correct incoming dial-peer which is configured with the only G711alaw Many time call will match wrong incoming dial-peer, which will result in such issue.

*** Please rate helpful post; Mark "Accept as a Solution" if applicable

Thanks,
Haris

[HARIS_HUSSAIN]

Disable from CUCM Service Parameter G.711 mu-law Codec Enabled:- Set it to disabled.

[cid:086d4824-b149-4c12-875b-c19867a544a7]

[ragz3000]

I want to use G711ulaw or alaw towards cucm/endpoint and g711ulaw towards telco. At the moment calls are going

[HARIS_HUSSAIN]

You can use
show call active voice OR
show sip-ua call

*** Please rate helpful post; Mark "Accept as a Solution" if applicable

Thanks,
Haris