SIP PRACK METHOD and Qo S 1 Agenda

SIP PRACK METHOD and Qo. S 1

Agenda SIP PRACK method(RFC 3236) SIP Qo. S SIP in 3 G + Qo. S 2

SIP Basic Call Flow Server (Callee) Client (Caller) User Agent INVITE+SDP 100: Trying 180: Ringing 200: OK+SDP ACK 3 RTP

SIP defines two types of responses, provisional and final. CLASS 4 Description 1 xx Provisional response : Informational 2 xx Success: Request has completed successfully 3 xx Redirection: Request should be tried at another location 4 xx Client-Error: Bad request…. . 5 xx Server-Error 6 xx Global-Failure: busy….

Provisional responses is unreliability. 提供打電話過程的資訊，一些臨時性的回應 trying (100), ringing (180), queueing (182), session progress (183). 不會回傳ACK Final responses is reliability. 每隔一段時間重送, 直到收到ACK 5

SIP Basic Call Flow Server (Callee) Client (Caller) User Agent INVITE+SDP(80 K) 100: Trying 180: Ringing 200: OK+SDP(50 k) CANCEL 6 無法建立連線

通訊建立初期會發生的問題 Session time 太長 SDP交換資料不足 Qo. S來不及處理 Need more negotiation. 某些情況下我們需要Provisional responses reliability 與PSTN連線, Session太長 Application server, wireless phones, media servers… 電話鈴聲響起之前(180 ringing傳送前)，必須把所有事 情都準備好。 7

SIP PRACK method Reliability of Provisional Responses in the SIP (RFC 3261) 讓 Provisional Responses 也有ACK回應 有更多訊息、時間可以做Qo. S或媒體溝通能力的準備 8

SIP PRACK Server (Callee) Client (Caller) User Agent INVITE+SDP 183 Session Progress +SDP PRACK (回應183) 200: OK (回應 PRACK) 9

S -> C : SIP/2. 0 183 Progress Require: 100 rel Via: SIP/2. 0/UDP saturn. bell-tel. com RSeq: 776655 From: sip: alexander@bell-tel. com; tag=736 ad 7789 To: sip: watson@bell-tel. com; tag=11 C->S: PRACK sip: watson@mypc. bell-tel. com SIP/2. 0 RAck: 776655 1 INVITE Via: SIP/2. 0/UDP saturn. bell-tel. com From: sip: alexander@bell-tel. com; tag=736 ad 7789 To: sip: watson@bell-tel. com; tag=11 Call-ID: 70710@saturn. bell-tel. com CSeq: 2 PRACK Content-Type: application/sdp 10

SIP Qo. S B A INVITE + SDP 1 (Qo. S) 183: Progress + SDP 2 200: OK (PRACK) UPDATE +SDP 3 200: OK (UPDATE) +SDP 4 11 180: Ringing RESERVATION PRACK

CODEC使用頻寬範例 Codec Bandwidth (bps) Frame duration Frame size Raw pkt G. 711 64 kbps 15 ms 120 Bytes 85. 33 k bps G. 723. 1 G. 729 5. 3 - 6. 3 kbps 8 kbps 30 ms 10 ms 24 Bytes 10 Bytes 12 17. 06 k bps 24 k bps

Session Flow Procedure UE#1 S-CSCF#2 S-CSCF#1 INVITE SDP Final SDP Reserv Success Ringing 200 OK ACK 13 UE#2

INVITE Visited Network#1 UE#1 P-CSCF Home Network#2 Home Network#1 S-CSCF#1 I-CSCF#2 HSS Visited Network#2 S-CSCF#2 P-CSCF UE#2 INVITE+SDP 100 trying INVITE + SDP 100 trying Service Control INVITE + SDP 100 trying Location Query Response INVITE + SDP 100 trying Service Control INVITE + SDP 100 trying INVITE + SDP 14 100 trying

183 Session Progress + PRACK Home Network#1 Visited Network UE#1 P-CSCF Home Network#2 S-CSCF#1 I-CSCF#2 HSS Visited Network#2 S-CSCF#2 P-CSCF UE#2 183 (SDP) 183 (SDP) PRACK (Final SDP) Authorize Qo. S Resource PRACK (Final SDP) 200 15 OK 200 OK

Reserv Success (COMET) Home Network#1 Visited Network UE#1 P-CSCF S-CSCF#1 Home Network#2 I-CSCF#2 HSS Visited Network#2 S-CSCF#2 P-CSCF UE#2 Resource Reservation COMET COMET 200 OK 200 OK 16

Ring (180 Ringing) + 200 OK (Hang Up) + ACK Home Network#1 Visited Network P-CSCF UE#1 S-CSCF#1 Home Network#2 I-CSCF#2 Ring HSS Ring Visited Network#2 S-CSCF#2 P-CSCF Ring 200 OK Approval of Qo. S Commit 200 OK Ringback 200 OK Service Control 200 OK Approval of Qo. S Commit 200 OK ACK 17 UE#2 ACK ACK

References Reliability of Provisional Responses in the Session Initiation Protocol (SIP) , IETF RFC 3262 draft-ietf-sip-100 rel-04. txt Integration of Resource Management and Session Initiation Protocol (SIP) , IETF RFC 3312 3 GPP. TS 29. 962 18