el g711uLaw 1.28.18.57 60002 M31 OpenLogicalChannel g711uLaw 1.28.18.57 60002 OpenLogicalChannelAck OpenLogicalChannelAck Call Flow Examples 181 M34 OpenLogicalChannel g711uLaw 4.30.19.04 5004 M35 OpenLogicalChannel g711uLaw 4.30.19.04 5004 M36 OpenLogicalChannelAck M37 OpenLogicalChannelAck M38 ACK sip:gstibitz123@snailmail.com: SIP/2.0 Via: SIP/2.0/TCP 2.3.4.5:4344;branch=z9hG4bk32 Max-Forwards: 70 Call Flow Examples From: ksip:burroughs@h323-gateway.com>;tag=3q526g45 To: ksip:stibitz@proxy.com>;tag=1 Call-ID: 526272332146783569054 CSeq: 43252 ACK Content-Type: application/sdp Content-Length: 130 O=- 2890844577 2890844577 IN IP4 1.28.18.57 t=0 0 C=IN IP4 1.28.18.57 m=audio 60002 RTP/AVP 0 a=rtpmap: 0 PCMU/8000 M39 ACK b:gstibitz123@snailmail.com SIP/2.0 Via: SIP/2.0/TCP 3.4.5.6:5060;branch=z9hG4bK452.1 Via: SIP/2.0/TCP 2.3.4.5:4344;branch=z9hG4bK532 Max-Forwards: 69 From: <sip:burroughs@h323-gateway.com>;tag=3q526g45 To: <sip:stibitz@proxy.com>;tag=1926 Call-ID: 526272332146783569054 CSeq: 43252 ACK Content-Type: application/sdp Content-Length: 130 O=- 2890844577 2890844577 IN IP4 1.28.18.57 t=0 0 C=IN IP4 1.28.18.57 m=audio 60002 RTP/AVP 0 a=rtpmap: 0 PCMU/8000 10.7 3GPP Wireless Call Flow An example SIP 3GPP call flow is shown in Figure 10.7. Some of the 3GPP P-headers are not shown with their actual values-instead, " is listed. Also, some call flows show SDP in the PRACK, but this is only needed if another SDP offer is made-in this case, the initial offer is accepted. Also, PRACKs are not shown in response to the 180 Ringing response since it does not carry any SDP and does not need to be delivered reliably. In this call flow, the use of QoS preconditions is shown (as indicated by the Require: precondi- tion header field and the QoS attributes in the SDP). After the initial offer and answer in the INVITE and 183, the QoS setup is performed. When it has been done successfully, each side indicates in the UPDATE and 200 OK response in the SDP that the setup is complete. Only after that does the called UE begin 