CUCM 12.5 and Grandstream Phone

[maqsood ahmed]

i have a situation here , i registered GXP2140 IP Phone (grandstream) to cucm 12.5 as adv 3rd party sip phone using seperate sip profile, the problem is when GXP2140 calls into cisco phone , it rings one or two times and hangs up, but the other cisco phone continue ringing , like wise if i lift the handset of cisco phone as i hear the ringing immidetiely the call connects normally.

pcap traces from gxp2140 shows a busy ( 486) coming  from cucm side towards gxp2140.

any insight ?

[Vaijanath Sonvane]

Hi @maqsood ahmed ,

It may be possible that the Cisco Phone and Grandstream Phone are using different codec and CUCM trying to invoke Transcoder. Please check codec negotiation in packet captures.