Figure 9.3 Point ofpresences (POPs) IXCA IXCA IXCA Toll office Network Toll office IXC B IXC B IXC B Toll office Network Toll office POP POP POP Tandem Tandem offices offices End End offces offces LATA LATA 9.6
9.6 Figure 9.3 Point of presences (POPs)
Note The tasks of data transfer and signaling are separated in modern telephone networks:data transfer is done by one network,.signaling(信令)by another. 9.7
9.7 The tasks of data transfer and signaling are separated in modern telephone networks: data transfer is done by one network, signaling(信令) by another. Note
Figure 9.4 Data transfer and signaling networks SCP SP:Signal point Database STP:Signal transfer point Signaling network SP STP STP STP Data transfer network 9.8
9.8 Figure 9.4 Data transfer and signaling networks
Figure 9.5 Layers in SS7 MTP:Message transfer part SCCP:Signaling connection control point TUP TCAP:Transaction capabilities application port Upper layers TCAP ISUP TUP:Telephone user port ISUP:ISDN user port SCCP Network layer MTP level 3 Data link layer MTP level 2 Physical layer MTP level 1 9.9
9.9 Figure 9.5 Layers in SS7
9-2电话调制解调器 传统的电话线路可以传送颜率范围是 300~3300Hz的信号，提供给信号的带宽是3000Hz。 整个颜率范围用于传输语音，在不丢失可识别性的 情况下，有一些干扰和失真是可以接受的。 本节过论的主题 调制解调器标准 9.10
9.10 9-2 电话调制解调器 传 统 的 电 话 线 路 可 以 传 送 频 率 范 围 是 300~3300Hz的信号，提供给信号的带宽是3000Hz。 整个频率范围用于传输语音，在不丢失可识别性的 情况下，有一些干扰和失真是可以接受的。 调制解调器标准 本节讨论的主题: