I have an issue that the outbound calls give one ring only and the voice gateway send a bye message with error " Cause=96 Mandatory IE missing error" we send the error to the SP , but they send that the GW is sending the bye message and you have to check from your side , however the incoming call from the provider is working fine.
Call Flow : Cisco phone ( IP Communicator / hard IP Phone) --- > CUCM ---> sip Cisco VGW ---> E1 PRI
Running configuration , outbound call logs , inbound call logs and call history is attached
NOTE : In the Call history ( we have a strange behavior that the PRI has codec g729r8 )
Telephony call-legs: 1 SIP call-legs: 1 H323 call-legs: 0 Call agent controlled call-legs: 0 Total call-legs: 2 0 : 25340 681429840ms.2046 (*11:42:58.094 DXB Tue May 23 2023) +8940 +8950 pid:100 Answer ******* dur 00:00:00 tx:0/0 rx:0/0 56 (call cleared (86)) dscp:0 media:0 audio tos:0x0 video tos:0x0 IP 0.0.0.0:0 SRTP: off rtt:0ms pl:0/0ms lost:0/0/0 delay:0/0/0ms g729r8 TextRelay: off Transcoded No media inactive detected:n media contrl rcvd:n/a timestamp:n/a long duration call detected:n long dur callduration :n/a timestamp:n/a