RTP over CUCM without hardware media resources

[mcaldogne]

Hello!

We are moving to another ITSP and have a SIP trunk directly from the CUCM to their gateway.

Would it be possible to route all RTP traffic through the CUCM? I tried to check "Media Termination Point Required" and assign a Media Resource Group with the CUCM resources, the RTP traffic is going from the gateway to the IP-phone. 

Thanks 

Mirko

[Roger Kallberg]

No you can not do that.

Apart from this it is a very bad idea to have a SIP trunk directly between your CM and a service provider as you would expose your entire network to the service provider. Strongly recommend you to use an SBC to form a demarcation point between your network and the service provider. You can use a regular Cisco router with dual network interfaces for this as long as it has UC services license and SIP session licenses.

[mcaldogne]

Hi Roger,

thank you for your reply.

No worries about security because the service provider is another "department" of our company, so the connection is secure and permit only the traffic between the CUCM and the other side, and this is a dedicated interface for this service.

So I am wondering if it would be possible to exclude hardware resourcesf for this purpouse.

I tried to set software only resources on the SIP trunk, but by a incoming call the RTP traffic is going from the remote gateway to the  IP-phone. By an outgoing call the SDP part is migging ant in the CCM I can find this message:

2022/12/20 17:35:48.379|MRM|ERR|MTP|no MTP resources are available|38484536|2,100,251,1.8500166^*^*

Do you mean it would be possible?

[Roger Kallberg · Accepted solution]

I already gave you the answer to that.

You can not get the media stream to go from the device to CM and then to your "service provider".

The MTP in CM does simply not have this capability. You would need to have a hardware MTP for that and if you anyway need to use a hardware device as the bridge between your network and the service provider network it is much better and simpler to use the hardware as an SBC. But it's up to you, just my strongest recommendation to do it that way as it would save you a few grey hairs and headaches.