Government Computer News
VOIP can save money, time
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Image: Henrik G. de Gyor
Lucent’s EBS portal provides directory lookup and gives teleworkers and travelers all their office phone functions, even instant messaging.
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The last time the GCN Lab tested VOIP, we found that IP phones with browsing capability operated at a snail’s pace and sometimes crashed. Connections sounded distorted at both ends. Service took a long time to set up. And when we placed an international call with “911” in the middle of the string, the call was forwarded to the police.
Two years is a long enough time to mature, and VOIP has indeed advanced by leaps and bounds. Today VOIP isn’t only economically attractive compared with land lines, but it also streamlines enterprise communications by organizing telecommuters, travelers and office users under one central system.
There are various types of VOIP networks. We chose to test an IP Centrex, or central office exchange, topology because it’s the easiest to set up and use. More important, IP Centrex can combine analog and IP phones under one system with many services for remote as well as local users.
Overall, IP Centrex is a very attractive option to landline telephony when you count in services such as agency directory assistance and other intranet functions.
Unlike a private branch exchange, or PBX, which requires expensive hardware operating at your agency site, IP Centrex service is remotely hosted by carriers such as AT&T Corp. and Verizon Communications Inc., much like a home telephone.
The main benefit, besides not needing expensive setup or human administrators for the hardware, is that IP Centrex can accommodate existing analog lines while bringing in VOIP phones. Unlike IP Centrex, an IP PBX system puts land lines and IP phones both through to the PBX, which funnels their signals to a switch, usually a Class 5 switch. The switch makes a primary-rate-interface connection to the public switched telephone network before it passes on the calls.
In contrast, an IP Centrex network does not need to make any PRI connections. Analog phones communicate directly with the public network through a Class 5 switch, and IP phones connect through a gateway server to the switch, which in turn releases the signals to the public network.
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