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NATTING SIP phone lines


anyone knows if there is a configuration of a Cisco Router with voice functionalities to act as a SIP phone?

A customer's scenario is the following:
- the customer has no.5 SIP phone
- each phone has its own number registered to an external SIP provider
- external SIP provider can't establish a trunk SIP with customer router that is a Cisco 2821 with voice functionalities

I am wondering if a Cisco 2821 router could do the following:
- register IP phones on router (with SIP or SCCP)

- register SIP lines provided by the external VoIP provider directly from router
- route the calls from ip phones to SIP PBX of my provider through Cisco 2821 based on some policies defined on the router without configuring a SIP Trunk.

In this way the router behaves, in the VoIP world, similarly when running NAT for IP address.

Is it possible?

thx in advance


Everyone's tags (2)
Hall of Fame Super Gold

Re: NATTING SIP phone lines

Yes, a router (CME) can do all these things, with some limitations.

However, you need a reputable consultant or cerfied cisco partner to configure these, otherwise nothing will ever work.