Despite the buzz, VOIP still has hurdles to overcome

CHICAGO'The movement of voice traffic onto data networks is seen almost as inevitable, and administrators are readying their networks for voice over IP.

In an April survey of federal, state and local IT officials by Network General Corp., 57 percent of respondents named VOIP as the most important network initiative they face for the coming year.

Jim Vale, product manager for the San Jose, Calif., company's Sniffer Voice performance analysis tool, said organizations are planning now for investments needed in the next budget cycle to support VOIP.

'That is a healthy sign,' Vale said. 'It is an indication that the technology has matured to the point that it merits large investment.'

But moving VOIP from test beds onto production networks requires ironing out some wrinkles remaining in the new technology, including security, protocol selection and support for services such as 911 emergency calls.

VOIP is a hot topic on the floor of this week's SuperComm trade show, with vendors offering answers and options for these questions.

Network General has been offering Sniffer Voice since 2001 to analyze the performance of voice applications on networks. 'We've watched the willingness to invest in the technology show a steady growth pattern,' Vale said. '2004 appears to be an inflection point in the adoption' of VOIP.'

He said most customers now are in the piloting and testing phase of VOIP, but added they are moving with caution toward rollout of production applications. 'They know it to be a high-risk application,' because telecommunications is mission critical in every enterprise.

Only a handful of government organizations are moving beyond the pilot phase. 'In particular, Defense,' Vale said. 'That is an area where we have seen sizeable and creative implementations.'

Regardless of the momentum VOIP achieves, coexistence will be the watchword for a long time, said Chris Thompson, product manager for Adtran Inc. of Huntsville, Ala.

'Analog phones will probably have to be supported for the foreseeable future,' Thompson said.

Adtran announced its new line of VOIP gateways, the Total Access 900 series of integrated access devices. The 900 series supports legacy analog systems with multiple analog interfaces as well as PBX handoff and Ethernet LAN and T1 WAN connections. The new series also supports the Session Initiation Protocol.

'The 900 series is Adtran's first foray into SIP end points,' Thompson said.

SIP is an application-level signaling protocol for setting up, maintaining and terminating multimedia sessions, including voice. It is an alternative to the more widely deployed H.323 standard from the International Telecommunications Union, and is better suited for the Internet.

'One of the complaints of H.323 is that it is too heavy, too complex,' Thompson said. 'SIP has quite a bit of marketing behind it and a great deal of potential. Not that it's going to be the end-all and be-all, but it's the one that seems to have the traction right now.'

The Total Access 900 also can be used for least call routing and for 911 call routing. A call admission override feature will ensure that emergency calls go through even if bandwidth is restricted.

But priority access for emergency calls does not solve the biggest challenge for 911 over VOIP. Enhanced 911 service, which is likely to be required soon of VOIP service providers, requires location-aware technology so that emergency calls can be routed to the proper location and emergency operators can know where the call is coming from.

One of the disadvantages of VOIP is that phones are not tied to a particular location'meaning that emergency calls may not go through at all, they may go to the wrong location and operators may not be able to tell where the call is coming from.

Because this has created problems for some VOIP customers, the Federal Communications Commission last month proposed a new rule that would require VOIP carriers to offer e-911 service as a standard feature. Carriers would have to connect to the proper public service answering point and also provide operators with location and callback information.

TeleCommunication Systems Inc. of Annapolis, Md., has a system that provides this service for VOIP. The company's background is in wireless communications, and it developed the system for delivering e-911 over cellular service. Applying it to VOIP is a logical step, said Timothy Lorello, senior vice president at TCS.

'We recognized that VOIP providers were going to need to be able to support e-911 in very much the same way wireless does,' Lorello said. 'We were very concerned that e-911 was going to be stumbling block for VOIP.'

The first challenge to overcome is that telephone equipment at public safety access points can automatically reject nonlocal phone calls. This means a 911 call from a cellular or VOIP phone with a nonlocal number would be blocked, even if the call were placed from nearby.

'We created a spoof,' to get around this, Lorello said. 'We fool the switch and the PSAP into thinking it is receiving a call from a local telephone number.' When the PSAP server queries the switch, the TCS system provides the actual phone number and location of the caller.

TCS provides this as a managed service for VOIP carriers, with calls routed through a primary call center in Seattle and a backup in Phoenix. The system still requires that be able to determine the location of the VOIP caller.

'Getting the location is the toughest part of the process,' Lorello said.

Techniques for determining location include triangulation of signals for wireless, recording port location for VOIP and GPS signals for both wireless and VOIP. But although GPS is becoming more commonly available in handsets, the most common technique requires users to register their location, which is recorded in the service provider's database.

The TCS system is agnostic about the technique used to determine location, as long as the location is available, Lorello said. 'Right now, the one that is in play is self registration.'

About the Author

William Jackson is a Maryland-based freelance writer.

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