Refer to the exhibit. Which SIP URI should be dialed in order to reach the endpoint that is registered with the IP address of 172.29.1.221 from another endpoint with a URI of sip:[email protected]?

52900121 is a numeric dial string that maps to a different service or endpoint, not a SIP URI targeting the endpoint registered at 172.29.1.221.

sip:[email protected] is the only fully qualified SIP URI that includes both the required 'sip:' scheme and the correct domain (osl147.local) where the endpoint at 172.29.1.221 is registered. The VCS matches the domain portion of the URI to its registration table to resolve the call to the correct IP address.

[email protected] references the wrong VCS domain (osl148 instead of osl147), so the call would not resolve to the endpoint registered at 172.29.1.221.

Dialing a raw IP address is not a valid SIP URI format when originating from a URI-based SIP endpoint and would not be processed correctly by a SIP proxy or VCS.

ex90 is an incomplete URI because it lacks the '@domain' portion required for inter-domain SIP routing, making it ambiguous or unresolvable outside the local domain.