Examples of IP Phones

The large telecom equipment manufacturers, such as Lucent and Nortel, are addressing the IP phone market with just one or two models, compared with the wide variety of telephones that they previously made for their legacy Centrex and PBXs. Presumably these vendors hope to rationalize their production line and minimize the costs of making large quantities of a standard set. The first generation of IP phones from these large companies, including Cisco, were proprietary devices that could only be used with that vendor's switches. The trend now is to produce sets that are based on the SIP or Megaco standards, or both.

Other independent phone suppliers (such as Aastra, Avanti, Pingtel, Telcordia, and Telrad) are offering intelligent, voice-over-IP phones to complement the features of IP-Centrex. Well-established, high-volume handset producers, such as Samsung and Sony, are also supplying this market.

Two telecom manufacturers, Mite1 and Siemens, have earned a reputation for ergonomically excellent telephone terminals, and both produce a range of IP phones. Mitel has five IP phone models, including a low-cost, single-port unit and the 5140 IP Appliance, which is pictured in Figure 3. The more expensive device has a 320-by-240 pixel display and an infrared adapter (IrDA) interface, which provides a link to (personal digital assistants) PDAs. This phone enables users to define icons to represent telephony features, using the Palm-based graphical interface.


Figure 3: Mitel's 5140 IP Appliance. (Reproduced with the permission of Mitel Networks.)

The Mitel 5140 also has a built-in Hypertext Markup Language (HTML) browser and integrated directory management capabilities. It can be used as an agent's or supervisor's workstation in an automatic call distribution (ACD) configuration.

An interesting and forward-looking type of IP phone is one that is essentially a PDA cradle, built to accommodate a Palm Pilot or a similar device. The PDA provides a color screen display and most of the processing power, as well as its built-in operating system, applications, and database. This keeps the cost of the phone itself very low and provides a powerful desktop terminal.

The Siemens IP phone brand is optiPoint; these were the first sets from a major telecom manufacturer to support SIP. The optiPoint 100, for example, has both 10 Mbps Ethernet and RJ-45 interfaces and includes the G.711 (64 Kbps) and G.723.1 (5.3 Kbps) voice encoding algorithms. It has a two-line, 24-character display and is a hands-free, speakerphone set.

A major advantage with IP phones is that, when moved, these phones automatically reregister with the communication system, providing access to the voice services within a few seconds. Most IP phones also integrate with HTTP-based system management packages to allow for fast and intuitive moves, adds, and changes (MAC).