Re: add G.711 in the INVITE

yuexp0929 · ‎04-13-2022

Hello All

My CUCM is 12.5. it connected to another PBX through SIP Trunk. I configured DSP that include G711 and G729 for all Phones. I found that INVITE only has G.729 when I make a call to the PBX through the SIP Trunk.

Can I add G.711 in the INVITE? Where Should I configure it?

Thanks in advance!

b.winter · ‎04-13-2022

Hi,

what's your exact call flow? Are you doing an outbound call from CUCM to PBX?

Where does this "DSP" come into this scenario?

Normally, CUCM does delayed offer, so in the INVITE there should be no SDP (therefore no Codecs advertised).

Could you post a trace of a call?

Shalid Kurunnan Chalil · ‎04-13-2022

Hi,

Could you please check and let us know what codec used from Phone to CUCM SIP trunk and also the Early Offer support for voice and video calls configuration in the sip profile used for the SIP trunk

you can try below,

Configure the Codec G711 (Region - Phone to SIP Trunk)

Configure Best Effort Early Offer in the SIP profile and then the Media Termination Point Required box is unchecked.

Note: CUCM is capble of both early offer and delayed offer. Best Effort Early Offer provides the functionality to offer early offer without using the MTP and based on the calling device. If the call is being originated from a Cisco IP phone you can expect call manager is sending an early offer with the codec assigned in the region.

Found an old Cisco live slide which demontrate the early offer with best effort -

Above configuration should work, but incase if you want to force the early offer with MTP in use. Check the "Media Termination point required" and ensure that the codec is selected G711ulaw. It is not recomended but there are some cases it is absolute require.

Edited to add few notes in the original post.

Regards,

Nithin Eluvathingal · ‎04-13-2022

Configure the Region Which use G711 add this region on the device pool and apply this device pool on the PBX TRUNK

Configure MRG and add the MRGL on the device pool apply this device pool on the PBX TRUNK. Make sure to check 'Media Termination Point Required" on the trunk. You can also apply the MRGL on the Trunk.

Restart the trunk and test the call.