rocedure for outgoing SMS messages is shown in Figure 10.7. P-CSCF S-CSCF IP-SM-GW IWMSC SMS / SMS-SUBMIT / RP-DATA SIP MESSAGE SMS / SMS-SUBMIT / RP-DATA SIP MESSAGE SMS / SMS-SUBMIT / RP-DATA SIP MESSAGE SMS / SMS-SUBMIT / RP-DATA MAP FORWARD SHORT MESSAGE SMS / SMS-SUBMIT SMS-SUBMIT-REPORT SMS-SUBMIT-REPORT / RP-ACK MAP FORWARD SHORT MESSAGE ACK SMS-SUBMIT-REPORT / RP-ACK SIP MESSAGE SMS-SUBMIT-REPORT / RP-ACK SIP MESSAGE SMS-SUBMIT-REPORT RP-ACK SIP MESSAGE Figure 10.7. Procedure at originating side for SMS over SIP 1) The message SMS/SMS-SUBMIT/RP-DATA is carried by the SIP MESSAGE message between the mobile and the proxy call session control function (P-CSCF). The identity of the request contains the public service identity (PSI) of the SMS-SC entity. 284 VoLTE and ViLTE The SIP MESSAGE message indicates in the header Content Type that the message body contains an SMS message. MESSAGE sip:sc.homeA.net SIP/2.0 Content-Type: application/vnd.3gpp.sms 2) The message SMS/SMS-SUBMIT/RP-DATA is carried by the SIP MESSAGE message between the P-CSCF and serving CSCF (S-CSCF) entities. The P-CSCF entity inserts in the header P-Asserted-Identity the uniform resource identifier (URI) of the origin of the SMS message. MESSAGE sip:sc.homeA.net SIP/2.0 P-Asserted-Identity:<sip:alice@homeA.net> - Content- - Type: application/vnd.3gpp.sms 3) The S-CSCF entity analyzes the received message and the initial filter criteria (iFC) to determine the destination of the SIP MESSAGE message. The message SMS/SMS-SUBMIT/RP-DATA is carried by the SIP MESSAGE messages between the S-CSCF and IP-SM-GW entities. 4) The answer 202 Accepted acknowledges the SIP MESSAGE message received by the IP-SM-GW entity. 5) to 8) The messages are identical to those exchanged for SMS over SGsAP, the IP-SM-GW entity playing the same role as the MSC server entity. 9) The message SMS-SUBMIT-REPORT/RP-ACK is carried by the SIP MESSAG message between the IP-SM-GW and the S-CSCF entities. The identity of the request contains the URI identity of the mobile origi