Ghost Calls Reported When User Does Not Answer Call (Doc ID 2118015.1)

Last updated on MAY 15, 2017

Applies to:

Acme Packet 4500 - Version S-Cx6.4.x and later
Information in this document applies to any platform.

Symptoms

Service Provider SBC customers were making international calls and when calling party abandons the call while its ringing, the called user is later called several times after a few minutes without an effort from the A side (Ghost call).

When the called party answers these ghost calls there is no audio.

If the calling party carrier does a search they see only the failed call and not subsequent attempts. When we look for traces in Service Provider network (where we have SBC) we see that several calls are initiated from the SBC to three of the soft switches with the same call-id.

So, in summary, one call comes to SBC, goes to one soft switch. During ringing calling party abandons (send a cancel, which is responded by 487 Request Terminated). After some time SBC sends another invite to second soft switch with same call-id and then the third.

When calling party disconnects the call (while its ringing), the Called party receives the same call, and when answered there is no audio at all.

Cause

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