How can I make a CUCM-integrated C40 make H323 calls as well?

[kylebrogers]

I have a CUCM-integrated C40 in a DMZ.  It works great for internal calls to other phones on the system.  However, when I try to dial an IP address, I get an almost immediate "call failed" and the firewall logs imply that it is actually trying to communicate with the CUCM via SIP instead of communicating outbound via H.323.  I have the H323 network service enabled on the C40 and I have H323 configured with the public IP that is being NATed to the C40, etc.  The NAT is set up on the firewall, the C40 is allowed to communicate on all ports outbound (and I have all the recommended ports open inbound).  Is there a way to specify to the C40 that a call needs to be an H323 call (as a standalone device) rather than a call controlled by CUCM?

[Nick Halbert-Lillyman]

H323 calls are not supported when registered to CUCM.  You either need to register as SIP and H323 to VCS, or use VCS to interwork from SIP to H323.

All that said, even when using VCS for interworking, there's no native IP dialling from CUCM, although you can "fake it" with SIP route patterns such as 'ip@[ipaddress]' then send the call to VCS which can strip the 'ip@' portion.

I know this probably isn't what you were looking to hear, but CUCM based integrations are very much SIP centric with H323 interoperability being less capable than VCS or stand alone deployments.