Service URN, location conveyance, and the FCC MLTS page. State PSAP rules are not invented here.
Emergency calling uses the service URN urn:service:sos, defined in RFC 5031. RFC 6881 is the Best Current Practice for communications services in support of emergency calling. The Request-URI on the synthetic INVITE is that URN.
Enterprise SIP has to carry location according to those documents and the current national rules. This lesson does not invent a state PSAP procedure, a PSAP address, or a civic record. The production location value is the one those documents and the national rules describe.
RFC 6442 specifies location conveyance for SIP, including the Geolocation header. The ladder shows Geolocation and Geolocation-Routing so you can see the header names. The cid body is not attached. A real request carries the location by value or by reference the way RFC 6442 specifies.
Read the location as part of the emergency request, on the same Call-ID as the INVITE. A call that reaches an emergency route without location has missed this requirement even if a 100 Trying came back.
Room: Emergency calling, location, and the FCC page
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