CUCM 12.0 Ad-Hoc conference with third party SIP-phone

[rajarshi.basak]

A third party sip-phone was getting back 403 Forbidden after sending an Invite to Conference Factory URI as host to initiate ad-hoc conference with cucm 12.0. But SIP trunk messaging guide says "The conference initiator calls the conference server using INVITE(Conference Factory URI) to begin a conference. The AS-SIP-EI conference factory URI looks like confFactoryDigitString@UCMaddress. The UCM routes the request via normal DA dialplan routing using confFactoryDigitString.". Any idea why I am getting 403 back after sending invite to the Conference factory URI?

[dstaudt]

Third party SIP phones are not supported with the CUCM ad hoc conferencing mechanism (which is based on non-RFC standard SIP protocol extensions and behaviours).

The only type of conferencing that would be able to work would be RFC SIP standard conferencing, which is managed (including audio mixing) onboard the phone itself - in which case CUCM is not aware of the conference, and there are no interactions with the CUCM ad hoc conferencing feature.