欢迎来到萝卜的空间

本空间所有日志信息或文章及相关资料皆萝卜原创或精心整理。如转载复制，请注明来源！建此空间的目的在于——以文会科技翻译同行，结识一批志同道合、志趣相投的译友，共同为科技翻译贡献自己的微薄之力！

续上表...

英文	中文
CALL DELIVERY TO THE IP NETWORK Figure 6. Message flow for iGSM call setup When an iGSM subscriber is in the IP network, call origination to the H.323 terminal follows standard H.323 call setup procedure. When the iGSM subscriber is in the GSM network, call originations from the MS and call deliveries to the MS follow standard GSM procedures [3]. The call setup procedure is described in the fol­lowing steps (the message flow is given in Fig. 6).	呼叫传递到IP网络 图 6  iGSM呼叫建立的消息流程 当一个iGSM用户位于IP网络时，向H.323终端发话的呼叫方（call origination）遵守标准的H.323呼叫建立规程。当iGSM用户位于GSM网络时，从MS发话的呼叫方以及发送到MS的呼叫传递都遵守标准的GSM规程。使用以下步骤描述呼叫建立规程（消息流程见图6）。
Step 1 — The caller dials the MSISDN of the iGSM subscriber. Consider an MSISDN number 0-936105401 in Taiwan. The first digit, 0, means a special service. The next three digits, 936, are used to identify the gateway MSC (GMSC) of the MS associated with the MSISDN. The origi­nating switch sends an SS7 Initial Address Message (IAM) to the GMSC to reserve the trunk.	第一步：呼叫方拨打iGSM用户的MSISDN号码，假定在台湾有一个这样的MSISDN号码0-93610540。第一个数字0表示特种业务。接下来的三个数字936，用于识别与MSISDN相关的MS的网关MSC（GMSC）。发话端交换机向GMSC发送一条SS7“初始地址”消息（IAM）以保存中继线。
Step 2 — The GMSC queries the location of the iGSM subscriber by sending the GSM MAP message SEND_ROUTING_INFORMATION to the HLR. Based on the received MSISDN, the address in the HLR record indicates that the iGSM subscriber is in the IP network. The HLR sends the PROVIDE_ROAMING_NO message to the gateway. The gateway translates the GSM MAP message into an RAS Location Request (LRQ) message with type RoamNo and sends it to the gatekeeper.	第二步：GMSC向HLR发送GSM MAP消息SEND_ROUNTING_INFORMATION询问iGSM用户的位置。根据接收到的MSISDN号码，HLR记录中的地址显示iGSM用户位于IP网络。接着HLR向网关发送PROVIDE_ROAMING_NO消息。接着，网关将GSM MAP消息转变成一条类型为RoamNo的RAS“位置请求（LRQ）”消息并将它发送给网守。
Step 3 — The gatekeeper generates the mobile station roaming number (MSRN) based on the address of the gateway and the H.323 terminal. An RAS Location Confirm (LCF) message with type RoamNoAck is sent to the gateway, and the gateway translates this message into the GSM MAP message PROVIDE_ROAMING_ NO_ack with MSRN. The HLR forwards the MSRN to the GMSC through the GSM MAP message SEND_ROUTING_INFORMATION_ack. Step 4 — Based on the received MSRN, the GMSC sets up the trunk to the gateway using the IAM message.	第三步：网守根据网关和H.323终端的地址产生“移动台漫游号码（MSRN）”。接着发送一条类型为RoamNoACK的RAS“位置确认（LCF）”消息给网关，然后网关将这条消息转变成带MSRN号码的GSM MAP消息PROVIDE_ROAMING_NO_ack。最后HLR通过GSM MAP消息SEND_ROUTING_INFORMATION_ack将MSRN转发给GMSC。 第四步：根据接收到的MSRN，GMSC使用IAM消息建立到网关的中继线。
Steps 5 and 6 — The gateway receives the MSRN of the iGSM subscriber. Through the Admissions Request (ARQ) and Admissions Confirm (ACF) message pair exchange, the gate­way uses the MSRN to obtain the terminal’s call signaling channel transport address from the gatekeeper. Steps 7 and 8 — The gateway sends the H.225 (Q.931) Set-up message to the H.323 terminal. If the H.323 terminal accepts this call, it replies with the Call Proceeding message to indicate that enough routing information has been received and it does not expect to receive more routing information from the gateway. Steps 9 and 10 — The H.323 terminal exchanges the ARQ and ACF message pair with the gatekeeper. It is possible that an Admission Reject (ARJ) message is received by the termi­nal and the call is released.	第五步和第六步：网关收到iGSM用户的MSRN号码。通过“Admissions Request（ARQ，允许接入请求）”和“Admissions Confirm（ACF，允许接入确认）”这对消息进行交换，网关使用MSRN从网守那里获取终端的呼叫信令通道传输地址。 第七步和第八步：网关向H.323终端发送H.225（Q.931）“Set-up”消息。如果H.323终端接受这个呼叫，那么它会回复一条“呼叫处理”消息，指示已接收到足够多的路由信息，不打算再从网关接收路由信息。 第九步和第十步：H.323终端通过网守对ARQ和ACF这对消息进行交换。终端可能会收到一条“Admission Reject（ARJ，接入拒绝）”消息并且挂机。
Step 11 — A ringing tone is generated at the H.323 terminal to alert the iGSM subscriber. The H.225 Alerting message is sent to the gateway. The gateway translates the message into an SS7 Address Complete message (ACM) and forwards it to the originating switch via the GMSC. Step 12 — When the iGSM subscriber answers the phone, the H.323 terminal generates the RAS Connect message to the gatekeeper. This message is translated into the SS7 Answer mes­sage (ANM) and is forwarded to the originating switch. At this point, the call path is established and the conversation begins. PSTN-IP call release follows the standard procedures defined in H.323 [7]. There is no need to create a new call release procedure for iGSM. The details are omitted.	第十一步：H.323终端产生振铃声，以提醒iGSM用户。向网关发送H.225 “Altering”消息。接着网关将该消息转变成“SS7 地址结束”消息（ACM）并通过GMSC将它转发给发话端交换机。 第十二步：当iGSM用户接电话时，H.323终端向网守产生“RAS连接”消息。接着这条消息被转变成“SS7 应答（ANM）”消息并被转发给发话端交换机。此时，呼叫线路就建立起来了并开始通话。 PSTN-IP挂机遵守H.323定义的标准规程。不需要为iGSM创建新的挂机规程。具体情况这里就不作介绍了。