Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

SIP Trunk RFC 2833 with G.729 media

Hi all, I recall there having been some issues back in CUCM 4.x with SIP Trunks not supporting G.729 when requiring RFC 2833 for DTMF.  Does anyone know exactly what the requirements are with CUCM 8 for SIP Trunking with G.729 if RFC 2833 DTMF is required?  Hardware MTP required?  DSPs required? etc.

Thanks.

  • IP Telephony
1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

Re: SIP Trunk RFC 2833 with G.729 media

You don't need DSPs for this; you can use an IOS software MTP for this, which just uses CPU cycles on the router.  Just make sure the IOS SW MTP is in it's own unique MRG, and that is at the top of the MRGL for the SIP trunk.

You shouldn't need to check 'MTP required' on the trunk, either.  CUCM will invoke the MTP if it needs it, depending on what the capabilities of the non-SIP trunk device is.

3 REPLIES
Cisco Employee

Re: SIP Trunk RFC 2833 with G.729 media

You don't need DSPs for this; you can use an IOS software MTP for this, which just uses CPU cycles on the router.  Just make sure the IOS SW MTP is in it's own unique MRG, and that is at the top of the MRGL for the SIP trunk.

You shouldn't need to check 'MTP required' on the trunk, either.  CUCM will invoke the MTP if it needs it, depending on what the capabilities of the non-SIP trunk device is.

New Member

Re: SIP Trunk RFC 2833 with G.729 media

Cool.  Thanks.  And will G.729 definitely work with IOS MTP?  I remember I had to use G.711 last time I was doing SIP Trunking...

Cisco Employee

Re: SIP Trunk RFC 2833 with G.729 media

Aaron,

Yeah, IOS SW MTP support g729 or g711.  SIP trunk support with CUCM has improved a lot since the 4.x days.

A couple things to note:

* If you plan on faxing across this trunk, find a SIP provider that supports T.38 and make sure all of your internal endpoints are T.38 capable (and can switch via protocol-based switchover.  i.e. 6608, vg248, and sccp-controlled FXS cannot).

* Will the provider require registration?  If so, you will need to put a CUBE between CUCM and the provider for this purpose.

* Does the provider needs to see early-offer (SDP in invite) for outbound PSTN calls?  If so, you will need CUBE and configure delayed to early offer.

822
Views
0
Helpful
3
Replies
This widget could not be displayed.