Calls Dropping off intermittently after few seconds

[tokunboah]

Hello folks, hope you are all keeping well.

We have a situation where calls are being dropped, sporadically, after few seconds.

We have two different SIP Trunks going to two different ITSP.

One uses prefix-8 dial-peer, and the other prefix-9 dial-peer.

prefix-9 Trunk works, with no issue.

prefix-8 Trunk works as well, for most calls. However, calls get dropped on this trunk, intermittently.

Sip logs on failed calls indicate that BYE is being sent from upstream. prefix-8 ITSP says our CUBE is not acknowledging their 200 OK header, and therefore issuing a BYE message.

However, pcap trace actually reveals two INVITE messages are sent on failed calls, one to our prefix-8 ITSP, which is the intended vendor, and one to the prefix-9 ITSP, which should not be part of any prefix-8 call at all.

Has anybody seen this behavior before? if yes, could they kindly shed some light, and possible solutions.

[Dennis Mink]

in your sip trace two public ip addresses are include 91. and 88. can you explain what these are?

[tokunboah]

Hello Dennis, many thanks for your response.

the "91.x.x.x" is the SBC address of the prefix-8 ITSP, while the "88.x.x.x" is the SBC address of the prefix-8 ITSP. These are two completely different SIP providers.

When we prefix any outbound call with 8, it goes straight to "91.x.x.x" ITSP.

When we prefix any outbound call with 9, it goes straight to "88.x.x.x" ITSP.