| 摘要 |
A mobile device/UE identifies calls to or callbacks from a Public Safety Access Point (PSAP) in order to provide priority handling. When the UE does not detect that the call being made is an emergency call, then the network facilitates identification during call establishment of the emergency nature. The network identifies the call as emergency call in a SIP response by setting the Priority header to distintive value (e.g.,"emergency-call") or the "P-Asserted-Identity to a distinctive value (e.g., urn:services:sos). When PSAP chooses to call back the mobile/UE, the mobile/UE can terminate any ongoing calls and accept this call from the PSAP and can disable other supplementary services (e.g., call waiting, three-way calling etc.) during the call. A P-Asserted-Identity of the incoming call is set to a distinctive location associated with PSAP (e.g., urn:services:sos). Alternatively, the incoming call has a Priority header set to a distinctive value (e.g., "emergency", "emergency-callback"). |
