综合业务数字网
逻辑特性 > ISDN呼叫举例

下面的例子是一个窄带（PRI）ISDN呼叫Q.921/LAPD和Q.931/混合网络消息（例如详细显示D信道的变化）。这个呼叫显示被跟踪的交换机呼叫另一个交换机的过程，最终的LEC中止通话。
第一行的格式是<时间><D通道><发送/接收><LAPD/ISDN><ID>。如果消息是ISDN层消息，解码操作就会试着显示信元内容。所有ISDN消息都用交换机看来发起呼叫的一方试用的ID标记（本机/远端）。Following this optional decoding is a dump of the bytes of the message in <offset> <hex> ... <hex> <ascii> ... <ascii>format.
RR表示开始通话前保持链路活动，然后看到的SETUP表示呼叫开始每一个消息对方都要应答一个RR。
10:49:47.33  21/1/24  R  RR
0000  02 01 01 a5                                          ....

10:49:47.34  21/1/24  T  RR
0000  02 01 01 b9                                          ....

10:50:17.57  21/1/24  R  RR
0000  02 01 01 a5                                          ....

10:50:17.58  21/1/24  T  RR
0000  02 01 01 b9                                          ....

10:50:24.37  21/1/24  T  SETUP
    Call Reference       : 000062-local
    Bearer Capability    : CCITT, Speech, Circuit mode, 64 kbit/s 
    Channel ID           : Implicit Interface ID implies current span, 21/1/5, Exclusive
    Calling Party Number : 8018023000 National number  User-provided, not screened  Presentation allowed
    Called Party Number  : 3739120 Type: SUBSCRB
0000  00 01 a4 b8  08 02 00 3e  05 04 03 80  90 a2 18 03   .......>........
0010  a9 83 85 6c  0c 21 80 38  30 31 38 30  32 33 30 30   ...l.!.801802300
0020  30 70 08 c1  33 37 33 39  31 32 30                   0p..3739120

10:50:24.37  21/1/24  R  RR
0000  00 01 01 a6                                          ....

10:50:24.77  21/1/24  R  CALL PROCEEDING
    Call Reference       : 000062-local
    Channel ID           : Implicit Interface ID implies current span, 21/1/5, Exclusive
0000  02 01 b8 a6  08 02 80 3e  02 18 03 a9  83 85         .......>......

10:50:24.77  21/1/24  T  RR
0000  02 01 01 ba                                          ....

10:50:25.02  21/1/24  R  ALERTING
    Call Reference       : 000062-local
    Progress Indicator   : CCITT, Public network serving local user, In-band information or an appropriate pattern is now available
0000  02 01 ba a6  08 02 80 3e  01 1e 02 82  88            .......>.....

10:50:25.02  21/1/24  T  RR
0000  02 01 01 bc                                          ....

10:50:28.43  21/1/24  R  CONNECT
    Call Reference       : 000062-local
0000  02 01 bc a6  08 02 80 3e  07                         .......>.

10:50:28.43  21/1/24  T  RR
0000  02 01 01 be                                          ....

10:50:28.43  21/1/24  T  CONNECT_ACK
    Call Reference       : 000062-local
0000  00 01 a6 be  08 02 00 3e  0f                         .......>.

10:50:28.44  21/1/24  R  RR
0000  00 01 01 a8                                          ....

10:50:35.69  21/1/24  T  DISCONNECT
    Call Reference       : 000062-local
    Cause                : 16, Normal call clearing.
0000  00 01 a8 be  08 02 00 3e  45 08 02 8a  90            .......>E....

10:50:35.70  21/1/24  R  RR
0000  00 01 01 aa                                          ....

10:50:36.98  21/1/24  R  RELEASE
    Call Reference       : 000062-local
0000  02 01 be aa  08 02 80 3e  4d                         .......>M

10:50:36.98  21/1/24  T  RR
0000  02 01 01 c0                                          ....

10:50:36.99  21/1/24  T  RELEASE COMPLETE
    Call Reference       : 000062-local
0000  00 01 aa c0  08 02 00 3e  5a                         .......>Z

10:50:36.00  21/1/24  R  RR
0000  00 01 01 ac                                          ....

10:51:06.10  21/1/24  R  RR
0000  02 01 01 ad                                          ....

10:51:06.10  21/1/24  T  RR
0000  02 01 01 c1                                          ....

10:51:36.37  21/