Cisco WS-X4604-GWY - VoIP Gateway Especificaciones descargar pdf (Pagina 44)

Chapter 2 Campus Infrastructure Considerations

Power to IP Phones

2-10

Cisco IP Telephony Network Design Guide

78-11103-03

the phone and PC to ports on different modules, thus achieving another layer of

redundancy by providing protection for one of the devices if either module goes

down.

The third option shown in Figure 2-4 differs from the others in that the phone is

not a hardware device, but is a JTAPI application running on a computer. This

option, the Cisco IP SoftPhone, could be particularly useful in environments

where the need for a separate handset is minimal.

Power to IP Phones

Cisco IP Phones support a variety of power options. This section discusses each

of the three available power schemes:

• Inline Power, page 2-10

• External Patch Panel Power, page 2-17

• Wall Power, page 2-20

Inline Power

The advantage of inline power is that it does not require a local power outlet. It

also permits centralization of power management facilities.

With the inline power method, pairs 2 and 3 (pins 1, 2, 3, and 6) of the four pairs

in a Category 5 cable are used to transmit power (6.3W) from the switch. This

method of supplying power is sometimes called phantom power because the

power signals travel over the same two pairs used to transmit Ethernet signals.

The power signals are completely transparent to the Ethernet signals and do not

interfere with their operation.

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Cisco WS-X4604-GWY - VoIP Gateway Especificaciones Pagina 44