Understanding SIP trunk on Internet backbone

[wilson_1234_2]

My company has a 100Mbps Internet circuit with a 10Mbps SIP trunk provisioned with Internet. The person who ordered the circuit no longer is with the company, and no one seems to know a lot about it.

It has been decided to go with a different carrier for the Internet.

I have contacted the provider and they are saying the SIP trunk was provisioned separate from the Internet.

But, I do not see how this is working:

Is the SIP trunk using the route table in the router where it and the Internet are terminated?

My understanding is that SIP is destined for a subnet we are advertising via Internet. When customers have a SIP call, are they routing to the IP Address advertised from the internet carrier, or do they have a direct link from the remote end to our end?

Any input would be greatly appreciated.

[Philip D'Ath]

It could possibly be delivered on a separate VLAN on the circuit from the provider.

It may also be simply controlled by the two IP addresses (your SIP IP address and the provider SIP IP address).  This combination of two IP address may be given 10Mb/s and everything else 100Mb/s.

Your provider should be able to answer your questions ...