Cisco Cisco TelePresence Video Communication Server Expressway
Call Failures
TLS Calls Fail when Unified CM uses SRV Trunk Destinations
Calls from Unified CM may fail if they use a TLS trunk security profile and SRV trunk destinations (requiring "_sips._
tcp" SRV record lookups in DNS).
tcp" SRV record lookups in DNS).
for up-to-date information regarding the versions of Unified CM
in which this issue has been fixed.
If you need to address one or more VCS peers you can work around this problem by not using SRV records. Instead, in
the SIP trunk, specify each VCS Destination Address individually using DNS A-records or static IP addresses.
However, note that these addresses affect the domain portion of the URI received by VCS from Unified CM. You may
need to set up appropriate transforms on the VCS to cater for this (see
the SIP trunk, specify each VCS Destination Address individually using DNS A-records or static IP addresses.
However, note that these addresses affect the domain portion of the URI received by VCS from Unified CM. You may
need to set up appropriate transforms on the VCS to cater for this (see
).
Encrypted Call Failures
Calls between endpoints registered to Unified CM and endpoints registered to VCS (or proxied via VCS) will fail if the
Unified CM endpoint requests best effort encryption and the other endpoint does not support encryption. (Unified CM
has a proprietary method for indicating fall back to no encryption - X-cisco-srtp-fallback – which VCS currently does
not support.)
Unified CM endpoint requests best effort encryption and the other endpoint does not support encryption. (Unified CM
has a proprietary method for indicating fall back to no encryption - X-cisco-srtp-fallback – which VCS currently does
not support.)
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Cisco VCS SIP Trunk to Unified CM Deployment Guide