I have question regarding running MLPP with 9971 IP Phones. I have configured MLPP in lab environment but MLPP with 9971 is not working. When trying to make a force call to phone I obtain the message from annunciator "The number you have dialed is busy and not equiped for call waiting or preemption".
I think the configuration is not a problem because when I used SCCP phones (7960, 7971) the MLPP was working as expected. The MLPP is configured on SCCP phone devices. In case of SIP phones I created "MLPP_CD" common device configuration and associated it with every SIP phone. (MLPP Preemption - Forceful, MLPP Indication - On)
Do you have any idea why 9971 SIP phones are not working?
CUCM version: 8.6.2
9971,9951 and 8961 are considered AS-SIP devices that need different configuration related to MLPP check below link:
once it configure , in order to use Precedence call, pick up the line/handset then precedence call softkey appear so press it then dial the destination number.