Sip trunk and cucm

[Horacio Gutierrez]

Hello,

Can someone explain to me why would you have a sip trunk from a voice gateway to call manager which has a PRI to PSTN. Also what's the purpose of the sip trunk to call Manager and what's would be the role of route patterns and dial peers in this scenario?

Thanks,

[Jaime Valencia]

Read the following chapters from the SRND for an explanation:

Gateways

Cisco Unified CM Trunks

Dial Plan

[Roger Kallberg]

You can integrate voice gateways to CM with a few different control protocols, SIP, H.323, SCCP or MGCP. This is the answer to the first part of your question. For the second part, routing from the CM towards an external entity, in this case the voice gateway,  is done via route patterns and dial peers is used in the voice gateway to configure the call path through it.