Exchange 2010 UM and CUCM 8.6 connection issue

[Tom Shaw]

We configured Unified Messaging in Exchange 2010 and a corresponding SIP trunk in CUCM 8.6 but when calling from an internal extension via IPC, we get a timeout (5 sec of silence and then busy).  We configured CUCM according to the below guide:

http://www.microsoft.com/en-us/download/confirmation.aspx?id=18298

And Exchange has been configured to mimic the Mitel Unified Messaging configuration that this will be replacing.

We are getting a SIP unavailable message (see below) in the CUCM logs and we do not see any entries when we turn up tracing in Exchange, so it appears that our call is not getting to the Exchange server or is being rejected/timing out.

(1459617833) SIP 503 Service Unavailable

I have attached the CUCM and Exchange config.  Any assistance is appreciated!

[Jonathan Schulenberg · Accepted solution]

What does a packet capture of the SIP dialog show?

Check basic stuff:

• Are all of the CUCM nodes in the Call Manager Group defined within Exchange UM?
• Are Exchange and CUCM both using the same protocol (TCP/UDP) and port for the SIP traffic?
• Is Exchange expecting a right-hand-side of the SIP URIs to be IP address or FQDN in the SIP traffic?

[Tom Shaw]

Hi Jonathan,

Thank you for your response.  We figured out today that IP does not resolve and switching the config in CUCM to use hostname resolved our connection issue (so good call on that last point!).

We now have a different issue.  Do you happen to know an easy way to repoint the UM mailbox policy or UM IP gateway to our new config (migrating from Mitel to CUCM)?  We can't recreate all of the existing configuration and we can't change the UMDialplan that is referenced.  As always, any help is appreciated!