Audiocodes Mediant 1000 SBC is truncating Call-ID longer than 128 characters making responses get the “SIP/2.0 481 Call/Transaction Does Not Exist” when call is sent from Digium SIP trunk

This is a documented Audiocodes defect. The defect ID is 150893 and is fixed in Mediant version v.7.20A.202.xxx.

The customer to examine the release notes for this version and if there are no changes that will affect them negatively, apply the latest update to their SBC to resolve this issue. 

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the device truncates the Call-ID to 129 characters. As a result, the SBC call fails. 

Applicable Products: All (SBC). 

https://www.audiocodes.com/media/13232/sbc-gateway-msbr-series-release-notes-ver-72.pdf