Call Setup Example 1

Call Handling in MSC Server System Call Setup Example 1© Nokia Siemens Networks 1 (12) translation. Indemnity The information in this document is subject to change without notice and describes only the product defined in the introduction of this documentation. The document has been prepared to be used by professional and properly trained personnel. INCLUDING BUT NOT LIMITED TO SPECIAL. Copyright © Nokia Siemens Networks 2008. Wave logo is a trademark of Nokia Siemens Networks Oy. Individuals can use the Nokia Siemens Networks training material for their own personal self-development only. Nokia Siemens Networks welcomes customer comments as part of the process of continuous development and improvement of the documentation. or performance of the mentioned hardware or software products are given “as is” and all liability arising in connection with such hardware or software products shall be defined conclusively in a separate agreement between Nokia Siemens Networks and the customer. 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Nokia Siemens Networks will. ............................................................................................................ 4 Originating RAB ...................................Call Setup Example 1 Table of Contents: 1 2 3 4 5 6 7 8 9 UE to MS Call with Fast Forward IP Bearer Establishment ..............................................Call Handling in MSC Server System ............................................................................................. 12 © Nokia Siemens Networks 3 (12) ...................................................................................... 5 IAM .................. 6 APM ....... 9 ACM ................................................................................................................................................................ 7 Core Bearer Establishment ...................................................................... 10 Alerting .................................................... 8 Terminating TCH ............................................................. 11 Answering............................................................................................................................ for instance if codec negotiation is necessary . it uses IP Bearer Control Protocol (IPBCP) to describe the IP bearer information such as IP addresses. ”Fast” means that the originating side resources are reserved prior to sending the IAM message. ”Tunnelled” means that the BICC protocol does not specify any functions or structures for IP bearer information.Call Handling in MSC Server System . Instead. The example shows fast forward bearer establishment. and using BICC call control signalling. UDP port numbers and codecs used. The bearer information is sent ”tunnelled” in the BICC IAM message in the forward direction and in the APM message in the backward direction. © Nokia Siemens Networks 4 (12) . ”Forward” means that the originating side reserves the bearer. Note that the delayed forward bearer establishment alternative is also supported by the MSS.Call Setup Example 1 1 UE to MS Call with Fast Forward IP Bearer Establishment This example illustrates the call set-up procedure for a 3G-to-2G call over an IP core network. If this is not possible .delayed forward setup must be used instead. The AAL2 bearer establishment is requested by the RNC with an ERQ ATM signalling message. the MSS asks for a RAB assignment. The message includes the MGW address.Call Handling in MSC Server System . The MSS responds with the RANAP CALL PROCEEDING message. The MSS requests an access side termination from the MGW and the MGW responds with bearer details.Call Setup Example 1 2 Originating RAB The RNC sends a SETUP message using RANAP signalling. Next. the RNC indicates to the MSS that the RAB assignment has been completed. the BCU-ID and other bearer parameters. © Nokia Siemens Networks 5 (12) . The MGW responds with an ECF message. The access side bearer is now established. Upon receipt of the AAL2 ECF message. The MGW then sends the bearer-related information (including the IP address and port number) with a Notify Request message .Call Setup Example 1 3 IAM In the case of an IP bearer. Since the Fast Forward bearer establishment method is used. © Nokia Siemens Networks 6 (12) . The MSS requests the network side bearer reservation from the MGW. bearer related) information. The MSS sends a BICC IAM message to the terminating MSS. With the network side termination reservation a one-way through-connection is established between the outgoing and incoming termination. the MSS always selects the core network side MGW for the call before sending an IAM towards the succeeding node. An MGW that has the IP connectivity towards the succeeding node is selected.Call Handling in MSC Server System .a procedure called Tunnel Information Up in 3GPP specifications .e.and the MSS acknowledges the message. the IAM contains the tunnelling (i. Now a BICC APM message. The network side termination is requested from the MGW. The MGW reserves the network side termination and acknowledges with an Add reply message. The BSC then responds with a CALL CONFIRMED message.including the selected IP address and port number .Call Handling in MSC Server System .in a Notify request message to the MSS. The Add request message contains the bearer-related information received in the IAM. Next. This is called Tunnel Information Down procedure in 3GPP specifications. the MGW sends its own bearer-related information . is sent to the originating MSS. including the bearer-related information of the terminating MGW. © Nokia Siemens Networks 7 (12) . The MSS responds with a Notify reply message.Call Setup Example 1 4 APM The terminating MSS sends a BSSAP SETUP message to the BSC after paging has been completed. Call Setup Example 1 5 Core Bearer Establishment The MSS sends the bearer-related information received in the APM message to the MGW in a Modify request message. The bearer over the backbone network is now considered to be established. At this point. both MGWs know each others IP addresses and other bearer-related information.Call Handling in MSC Server System . © Nokia Siemens Networks 8 (12) . Call Setup Example 1 6 Terminating TCH Next. The MSS hunts an outgoing circuit from the MGW and then sends a BSSAP TCH ASSIGNMENT REQUEST message to the BSC and the terminating side access bearer is set up. to use early termination reservation instead. © Nokia Siemens Networks 9 (12) . Note that this example assumes that the base station subsystem (BSS) side termination in the MGW is reserved after the core network bearer has been established. Upon receipt of the TCH ASSIGNMENT COMPLETE message. It is beneficial. however. a BICC ACM message is sent to the originating MSS. the terminating side MSS initiates the reservation of a TDM circuit towards the BSC. so that the MGW selection can be optimised.Call Handling in MSC Server System . © Nokia Siemens Networks 10 (12) . sends a Modify request command to the MGW. the two-way through-connection between the terminations is reached by modifying the Stream Mode setting of the access side bearer termination.Call Handling in MSC Server System . When Stream Mode is used in the MGW.Call Setup Example 1 7 ACM The originating side MSS. instructing the MGW to make a two-way through-connection between the access side and the network side bearer terminations. after receiving the ACM message. Call Handling in MSC Server System . which in turn sends a RANAP ALERTING message to the RNC. © Nokia Siemens Networks 11 (12) .Call Setup Example 1 8 Alerting The destination terminal is now ringing and the BSC sends a BSSAP ALERTING message to the MSS. The MGW connects the ringing tone. A BICC CPG message is sent to the originating MSS. The MSS requests the MGW to generate a ringing tone with an AddRequest message. The call is now established. Now there is a two-way end-to-end bearer connection. the BSC sends a CONNECT message to the MSS.Call Setup Example 1 9 Answering When the terminal answers. © Nokia Siemens Networks 12 (12) .Call Handling in MSC Server System . The MSS requests the MGW to disconnect the ringing tone and to make a throughconnection between the access side and network side bearer terminations. which in turn sends a CONNECT message to the RNC. An ANM message is sent to the originating MSS.