CUCM SIP trunking using UDP for signalling

[Mihkel Laur]

Hello 

We have a couple of products in our environment that we need to connect to via SIP trunk. 

Problem is, these products use UDP for SIP signalling.

So the situation is that when I create a SIP trunk to a product that uses UDP for signalling, CUCM shows that the trunk is down (SIP OPTIONS Ping). This is because it cannot create a TCP connection. Thus, CUCM does not route any calls to that trunk. 

Although, calls can be received via that trunk...

Is there some way to make CUCM route these calls despite the trunk showing status down? There is no SBC in between as these products are within corporate LAN.

CUCM v 12.5

[Roger Kallberg]

CM does not look at the status of the SIP trunk before routing a call via it. You’re problem with outbound calls is caused by something else.

[Mihkel Laur]

It turned out that one of the products does have TCP signalling capability (despite data sheet showing only UDP). Once signalling was reconfigured to TCP, CUCM trunk immediately went up and calls started going through. There were no other changes done. 

[Roger Kallberg · Accepted solution]

Sounds like you have configured your trunk for only TCP. Look at the profile set for the trunk and check the protocol set in it.

[Mihkel Laur]

Incoming transport Type is set to TCP+UDP in the SIP Trunk Security Profile Information.

Outgoing has option to choose only TCP or UDP or TLS and is set to TCP.

[Roger Kallberg]

There you have the explanation why it would not work with UDP.

[Mihkel Laur]

Will try it out with the second product in the coming weeks, will close this thread if this solves the question. 

Thanks for the input!

[Mihkel Laur]

Outgoing was set to UDP and this worked. 

Thanks for the input.