tailieunhanh - IP-Based Next-Generation Wireless Networks phần 5

bởi các HLR để xác định xem yêu cầu có thể được cấp và tìm kiếm cơ sở dữ liệu HLR cho các thông tin yêu cầu về điện thoại di động. Nhà cung cấp CVSE-Giá trị: Trường này có chứa dữ liệu nhà cung cấp / tổ chức cụ thể. Nó có thể chứa số không hoặc nhiều octet. | 152 IP MULTIMEDIA SUBSYSTEMS AND APPLICATION-LEVEL SIGNALING Originating Network Originating Home Network S-CSCF41 3a. Invite 3b 1. 6. Invite Initial SDP Offer 4. 1XX SHOO Qucn 5. Rt poflw 1 Invite Initial SDỊP Offer 2. Service Control I 10. Offer Response 15. Response Conf Opt SDP 20. Conf Ack Opt SDP 21. Reservation Conf 18. Conf Ack Opt SDP 12. Offer Response 13. Response Conf J 28. Reservation Conf 32. Ringing 36. 200 OK 26. Reservation Conf 30. Ringing 34. 200 OK 39. ACK Fig. S-CSCF to S-CSCF signaling flow 3b2. Invite Initial SDP offer I 7. Service Control I 8. Invite initial SDP Offer softer Response 16. Response Conf I opt SDP 17. Conf Ack Opt SDP 24. Reservation Conf 25. Reservation Conf 29. Ringing 33. 200 OK the SDP received from the destination mobile. Finally the destination mobile responds to the confirmation with an acknowledgment Conf ACK . After that the mobile issues a Reservation Confirmation Reservation Conf message which completes the resource reservation. Please refer to Chapter 6 for issues related to QoS Quality of Service and resource reservation indicated in Figures . The destination mobile is alerted by the incoming request by a ringing indication. The originating mobile may also hear the ring-back tone and is alerted that the destination is ringing. Once the destination mobile user answers the request a SIP 200 OK message is returned to the originating user which then responds with a SIP ACK message. In Figures the dotted-rectangular represents two optional flows. That is the flow may be relayed by the I-CSCF or it may bypass the I-CSCF. Although we explain the end-to-end session setup by Figures altogether each of the figures is independent and can be combined with other procedures. For instance the S-CSCF to S-CSCF signaling flow of Figures could be used with other 3GPP IP MULTIMEDIA SUBSYSTEM IMS 153 Originating Network Destination Home Network Visited Network 3bI. Invite Intial SDP Offer 4.