One way calls from CUCM to TelePresence

[wildflower1977]

Hi all,

I have configured my zones, dial plan transforms and search rules as according to the documentation for X7.2.2.  

I have configured a SIP trunk from the CUCM to the VCS-C address

I can successfully call from a CUCM device to a telepresence end point and establish a SIP video connection.  When I attempt to call the CUCM from the TelePresence end point it doesn't connect.  Within the VCS-C call history logs i have the following entry:

source: 4205@publicdomain.com

destination: 8415@publicdomain.com

Type: Non-traversal

Protocol: SIP <-> SIP

Status: 416 Unsupported URI Scheme

Peer: This System

under the view detail button it states:

Connection failed, disconnect reason 416 Unsupported URI Scheme

the only thing that looks odd (to me) is it is using Src-port="5061" Protocol="TLS" but the Auth="NO"

Does the CUCM require the Auth to be enabled or is this something else?

[George Thomas]

Is CUCM configured for mixed mode? ie. will it do SIP/TLS? If not, you might want to turn off SIP/TLS from the VCS side.

[wildflower1977]

ok, I have turned off the TLS mode and now get a different error code:

480 Temporarily Not Available

[George Thomas]

Did you try what Paul asked above? Also, have you checked the Incoming CSS on the SIP trunk - does it have access to the device you are trying to call. SIP logs from VCS/CUCM might help.

[wildflower1977]

yup, CUCM has both the internal and external domains added so that shouldn't be a problem.

I have disabled SIP/TLS on the VCS under the VCS configuration>protocols>sip>configuration menu

new error 480: no route for bandwidth calculation

[George Thomas]

Do you have any pipes created on VCS? I would suggest you remove the Pipes from the DefaultSZtoCUCMZone Links and see what happens. (This is just the basic recommendation, you might have other zones in play)

[wildflower1977]

at first I didn't have any pipes, I have added a pipe from the VCS to CUCM with unlimited bandwidth, still doesnt work

[Paul Woelfel]

Did you configure CUCM for the same Enterprise Top Level Domain? Otherwise you have to transform the URI in your search rule 8415@publicdomain.com to 8415@1.1.1.1

[wildflower1977]

Thanks to Paul and George for your insight on areas to investigate, I now have a working solution.

The issue was initially using TLS on the VCS when not supported by CUCM.

I then had to rework the search rule to identify the CUCM dialling pattern and do 'pattern behavior' replace to change the external domain for the internal domain.

Both domains should work 'in theory' as the CUCM enterprise top level domain field contains both, but only the internal domain actually works.