Cisco IP Phones
Cisco IP telephones provide the end-user with an interface into the IP telephony
architecture.There have been two generations of IP telephones produced by
Cisco: first-generation and second-generation.
Cisco’s first-generation IP telephones came with the acquisition of Selsius
Technologies.These telephones are now discontinued.There were two models of
the first-generation telephones: the 30 VIP/SP+IP telephones and the 12-Series
IP telephones, the latter being the most popular.These telephones had a very
limited, button-based feature set, while the network interface was a 10 Mbps hub,
with an extra interface for a PC or printer. Also, these phones require an external
power source, whereas second-generation phones can utilize inline power. Both
the 30 VIP/SP+IP telephones and the 12-Series support either G.711 or G.723.1
coder-decoders (CODEC), support Microsoft NetMeeting, H.323 support, and
DHCP/Boot P support.
While sharing many similarities with their predecessors, such as support for
open standards and the ability to interact with Microsoft NetMeeting, secondgeneration
phones represent a vast improvement over the first-generation phones.
Certain second-generation phones interface with the network via a 10/100 Mbps
switched connection, also providing an extra port for a PC or other peripheral
device, as well as an RS-232 port for additional capabilities. Second-generation
phones such as the 7940 and 7960 offer an LCD screen used for a menu-based
feature set as opposed to the button-based feature set of their predecessors.The
most impressive feature of the second-generation phones is the ability to utilize
inline power. Now instead of using an external power supply, these phones,
through the use of a specialized inline-power patch panel or specialized modules
for the Catalyst switch line, can be powered directly through their category-5
cable.We will discuss inline power options in the infrastructure section later in
this chapter.
There are currently four phones in Cisco’s second-generation phone offering:
The 7910/7910+SW phone
The 7940 phone
The 7960 phone
The 7935 phone
Cisco also offers a completely software-based logical IP telephone called the
IP SoftPhone.The SoftPhone provides an alternative to the hardware-based second
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38 Chapter 2 • New World Technologies
generation IP telephones. It offers a PC-based software application that interfaces
directly with the CallManager server to provide IP telephony.
The 7910/7910+SW, 7940, and 7960 are all end-user phones, the only difference
really being the features supported, such as menu options, speaker phone,
display, and number of lines each phone supports.
The 7960 stands out among its peers as being the only second-generation
telephone to offer support for the Station Initiation Protocol (SIP). SIP allows
the 7960 to operate without a CallManager on the local LAN. Instead, it communicates
directly with the gateway.The 7960 can be expanded further by use of
the 7914 expansion module.
The 7914 provides an additional 14 lines to your 7960 telephone, plus two
7914 units can be daisy chained together to provide an additional 28 lines of support.
This serves as a great solution for receptionist telephone stations.The 7935
is the speakerphone offering in the second-generation product line. Once again,
you should consult the Cisco Web site for the latest product offerings in this line.
Table 2.1 discusses the different features of the second-generation IP telephones.