Destination Cause Value 2801795135 - SIP Trunk call issue

[sarvan]

Carrier -- SIP Trunk -- Audio Codes SBC -- SIP Trunk -- CUCM -- CIPC/Phone

Inbound and outbound calls to CUCM receiving Destination Cause Value 2801795135 in CDR

CDR for Inbound - Destination Cause Value 2801795135 and Number not in use for caller, Called Party displays extension number but destination device shows NULL instead of CIPC

CDR for Outbound - Fast Busy with Destination Cause Value 2801795135, destination device shows NULL instead of SIP Trunk

Any feedback will be useful for troubleshooting. Thanks.

[Scott Leport]

https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/service/11_5_1/cdrdef/cucm_b_cucm-cdr-administration-guide-1151/cucm_b_cucm-cdr-administration-guide-1151_chapter_0110.html

According to this link, its a 503 Service Unavailable. 

Check the status of the CUCM to Audiocodes SIP trunk in CUCM. If using a SIP profile with Options Ping enabled, it will tell you status of the SIP trunk and how long it's been service, or how long it's not been in service. 

If your SIP trunk between CUCM and Audiocodes SBC is up, move your focus towards the Audiocodes. Don't know the product, but I am sure you can pull a packet capture from it to see what's going on.