7942G/7962G IP PHONES
The 7942G and 7962G IP Phones may be the two most deployed phone models in the Cisco IP Phone portfolio at present. They are significant evolutionary steps over their predecessors in that they brought wideband audio and Internet low bit rate codec (iLBC) into widespread production.
Each has a 4-bit grayscale display and dynamic backlit tricolor buttons (green/yellow/red for line status) for line appearances, speed dials, busy lamp field (BLF), intercom, or application use. The 7942 has two of these buttons; the 7962 has six.
These phones can be used with either SCCP or SIP. The figure below shows the 7942G IP Phone.
The form factor shown in the Figure above is common across the 794x/796x models with only minor differences, which are pointed out as each model is mentioned. The figure below shows the 7962G IP Phone.
The 7962G supports the use of up to two 7915 expansion modules (a.k.a. sidecars). The first expansion module can piggyback off of the PoE supplied to the phone by the access switch or external power supply.
The second expansion module can be used only by adding an additional external power supply. The expansion modules easily mount to the right side of the phone, or each other, in the case of multiple expansion modules. The figure below shows the 7915 expansion module.
7925G/7925G-EX/7926 IP PHONES
The 7925G, 7925G-EX, and 7926 models are 802.11a/b/g wireless handsets. They are hermetically sealed to avoid contamination by dust, liquids, and so on The exterior is coated in a rubber casing to aid in handling and provide some drop protection.
These handsets meet U.S. military 810F standards. Each of the models supports Bluetooth 2.0 with Enhanced Data Rate (EDR) hands-free profile. Also built in is a button for push-to-talk functionality that can be enabled via XML application integration.
One of the more interesting additions to these handsets is the introduction of an on-board Java virtual machine, which allows the handset to run Java MIDlets locally. This allows for customized content/information to be presented to the 2-inch color screen.
So, why choose one model over the others? Up to this point, they each seem relatively similar in form and function. The differences are somewhat based on the intended use of the phone and the environment in which it will be used. The figure below shows the 7925G model.
The 7925G is the general-purpose handset model and is the most widely deployed of the three. The 7925G-EX is ruggedized and built for hazardous environments. Its bright yellow color makes it stand out in any environment. It is Atmospheres Explosibles (ATEX) Zone 2 certified for use around hazardous gases, chemicals, and other potentially explosive environments.
The figure below shows the 7925G-EX handset sitting in an optional speakerphone/ charger cradle (compatible with all three models).
The 7926G has a built-in 2D image barcode scanner. This is useful in any environment wherein inventory/assets need to be tracked. The 2D barcode scanner is not a laser-based scanner. It uses light emitting diodes (LEDs) to illuminate the target barcode and takes a picture of it, which is decoded by the phone.
The resulting information is then relayed to a customer/partner developed backend system application for processing/storage. The 7926G looks identical to the 7925G in almost every way. As mentioned, the only real difference is the barcode scanner situated in the top of the handset. The figure below shows a top-down view of the handset to detail the barcode scanner.
CISCO 7900 SERIES PHONES
The 7900 series phones have long been the so-called workhorse of the line for many years now. These phones have undergone an unimaginable number of evolutions and revolutions over the years. Currently, this series includes the following models:
The 7900 series phones are grouped into families of sorts. These are based on their intended use/features. That said, the models listed here are discussed in their constituent family groups.
CISCO 7800 SERIES PHONES
The Cisco 7800 series phone are relatively new on the scene. They include a number of interesting enhancements over many of their IP Phone predecessors. These phones are designed for light- to high-use voice users and are meant to replace the recently retired 6900 series phones.
As IP Phone deployments grow and place very increasing demands on edge switch PoE capabilities, it becomes clear that there is a need for a high-feature phone with low power requirements. As Class 1 power devices, the 7800 series are built for just such environments.
There are four models in the 7800 series line:
Each includes wideband (G.722) audio support and backlit grayscale displays (apart from 7811 which has a monochrome display) and supports only SIP signaling. In addition, these phones support the Electronic Hookswitch feature used in many industry headsets today. They can be wall-mounted or placed on the desktop. Each model is available in charcoal or white.
The figure below shows the 7800 series phones.
CISCO 3900 SERIES PHONES
The 3900 series currently contains only the 3905 model as of the time of writing this article. Its predecessors, the 3911 and 3951, were retired in 2010. So, there is no real need to cover them here.
The 3905 is an entry-level, single-line, SIP-only handset. It addresses the need for basic dial tone at a very cost-effective price point. It is a single-line device, although it does support call-waiting. It has a small 128x32 pixel monochrome display but no programmable soft keys.
Therefore, it does not support XML applications. It is Class 1 Power over Ethernet (PoE) capable or can use an external power supply. It has an integrated 10/100 switch and speakerphone as well. The figure below shows the 3905 model phone.
As seen in the figure, there is a Message Waiting Indicator (MWI) in the top-right corner. It has eight fixed feature keys that provide access to several functions. The buttons just below the display include a Previous button (to go back one menu level), up and down navigation buttons, along with a Select button and a Settings button for phone configuration.
Just below the navigation pad is a row of three feature keys. These keys, from left to right, are Redial, Transfer, and Hold/Resume. Below the keypad is an additional row of buttons for Mute, Volume Control, and Speakerphone.
As is evident, the 3905 is purpose built to provide phone service in a hospital waiting room, hotel lobby, college dorm room, break room, hallways, or anywhere else requiring a simplified feature set. The phone can be wall-mounted or simply placed on a desk or tabletop.