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NO Internal calls between SIP phones when SIP trunk is set

I set a SIP trunk in CME4.2 to make calls to PSTN.

The only way I found in order to make calls was setting the outbound proxy (IP address) in

voice service voip

allow-connections h323 to h323

allow-connections h323 to sip

allow-connections sip to h323

allow-connections sip to sip

supplementary-service h450.12



bind control source-interface GigabitEthernet0/1

bind media source-interface GigabitEthernet0/1

subscription maximum accept 5

registrar server


outbound-proxy ipv4:x.x.x.x

My problems is that I can not make call between SIP phones (linksys phone)

I can just call from IPcomm to linksys phone.

How can I solved this issue??


Re: NO Internal calls between SIP phones when SIP trunk is set

I think the problem is with the SIP server they're using that apparently violates the standard so that the rotuer complains.

SIP trunks are similar to a phone line, except that SIP trunks use the IP network, not the PSTN. In addition, SIP trunks permit the convergence of voice and data onto common all-IP connections. In order to access the IP network using an SIP trunk, it is necessary that configurations be made on the service provider, as well as on the customer side. Customers need to set and configure CME, which is the PBX that will interpret the SIP signal adequately and pass traffic successfully. The service provider needs to configure an SIP Proxy Server. However, SIP trunks are more complicated to establish than regular PSTN trunks.

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