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Chapter 55 Configuring a VoIP Network
Understanding How a VoIP Network Works
Understanding How a VoIP Network Works
A telephony system built on an IP network instead of the traditional circuit-switched private branch
exchange (PBX) network is called an IP PBX system. (See Figure 55-1.) The system’s components are
described in these sections:
• Cisco IP Phone 7960, page 55-2
• Cisco CallManager, page 55-5
• Access Gateways, page 55-5
• How a Call Is Made, page 55-8
Figure 55-1 IP PBX System
Cisco IP Phone 7960
The Cisco IP Phone 7960 provides the connectivity to the IP PBX system. The IP phone has two RJ-45
jacks for connecting to the external devices: a LAN-to-phone jack and a PC-to-phone jack. The jacks use
either Category 3 or Category 5 unshielded twisted-pair (UTP) cable. The LAN-to-phone jack is used to
connect the phone to the LAN using a crossover cable; a workstation or a PC can be connected to the
PC-to-phone jack using a straight-through cable.
The inline power is designed to work in cables from Category 3, Category 4, Category 5, and later up to
100 meters. The inline power works with IBM Token Ring STP cable of 100 meters when used with a
Token Ring to Fast Ethernet adapter (LanTel Silver Bullet SB-LN/VIP-DATA adapter).
Analog Station Gateway
10/100BASE-TX Module *
(WS-X6348-RJ45V)
Analog stations
(phone, fax, modem)
WS-PWR-PNL
IP cloud
(WS-X6624-FXS)
10/100BASE-TX Module
* Catalyst 4000, 5000, and 6000 10/100 modules
Analog Trunk Gateway
Voice Gateway 200
Analog stations
(phone, fax, modem)
Cisco CallManager
Catalyst 6500 series switches
IP phone
PC
IP phone
PC
PSTN or PBX
PSTN or PBX
Digital Trunk Gateway
(WS-X6608-T1/E1)
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