This really isn't an SRST problem, but a 911 network misunderstanding.
If you don't have some type of E911 solution whenever you call 911 the PSAP will always see your Bill To Number and the location attached to that number no matter where in your campus you place the 911 call from. Basically the 911 PSAP network is a seperate voice network that routes calls based on the ANI and not the DNIS as the normal PSTN SS7 network does. Basically the Telco has Class V switches that tie into the 911 network along with location databases. So normal calls to 911 will always use the Bill to number of the PRI/circuit that you are calling from unless you have the provider provision a Transparanent Calling Party Number service on their Class IV/V switch. Bell south calls this service "PinPoint". This service will also allow the customer to provide location names attached to certain NPA/NXX values so that the PSAP will see the correct location ID when a call comes in from those phones. This location to NPA/NXX is contained in multiple ALI databases that in my area is handled by a company called Introtta which is contracted by Bell South.
Now, this doesn't address the mobility aspect of IP phones and location ID's. This would be handled by Emergency Responder which works with the CCM and LAN switches to form ERL (ER Locations) for IP Phones. IE. If I take IP Phone A from the Warehouse and plug it into the Medical center and make a 911 call, the PSAP will see the Location/DID originating from the Medical Center now since the switch port that we just plugged into was in the Medical ERL that had a certain ELIN configured.
Summary, if I have a PRI at the main location and I have a SRST/GW router in another location. I make a 911 call from the SRST/GW location the PSAP will see the call originating from the Main Site's PRI location and attached Bill To Number (main number). This will happen unless you have a transparent calling number service configured with your Telco.
Does this help?
Mike
