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The FCC's decision on May 19 to require VoIP providers to include basic E911 emergency number service to their subscribers, as a mandatory feature, highlights another critical aspect of the transformation to VoIP of telephony services. Enterprises must consider E911 as part of their VoIP pre-implementation planning process. Just as dial tone is perceived to be an intrinsic part of phone service, so is 911 emergency number service. But, as several well publicized situations — such as the Texas case involving Vonage — have shown, the ability of phone users to report an emergency by placing dialing “911” isn't automatic.

Early in my career, I was part of the Bell System team that introduced location information as part of emergency calling. This service, E911, provides the ability to not only connect a caller to the “nearest” public service answering point (PSAP), but, importantly, delivers, via a data network, the caller's location information (ALI), to the PSAP. This location information is important for two reasons — routing the call to the nearest PSAP, and delivering the address information to the PSAP so the location is identified even if the user is unable to speak. Since its introduction in the mid-1970s, E911 now serves almost 100% of the U.S. population and has saved many lives and improved the quality of emergency response for all of us.

E911 relies on capturing and delivering the caller's location information (ALI) to the emergency call response center. And it was designed and implemented based upon the fixed-location and line-powered Public Switched Telephone Network (PSTN). VoIP breaks this critical linkage in two important ways.

First, the IP network is not fixed — a phone number is no longer tied to a location. This location independence issue is still simmering — the issue that still hasn't been fully nor satisfactorily resolved in more than a decade.

Second, a VoIP phone is not likely to be powered by the telephone line and may not work at all during a local power outage (caused by a storm or fire) without backup battery power, from the wiring closet (power over Ethernet) or in the instrument itself. The VON Coalition and the National Emergency Number Association (NENA) have been working diligently to develop E911 standards for IP. But resolution and full implementation are still likely several years away.

Enterprise phone system planners and administrators, both PBX and CENTREX solutions, have always had special concerns regarding 911 services. Some of these are how to map the physical location of an extension to a identifiable location within a building or campus (such as building 1, third floor north corner) and whether a caller gets to the PSAP by dialing 911, 9-911 or either. Usually, a data base system linking the corporate directory to a location map is developed and this system provides a feed to the PSAP periodically. With moves and changes, this database may have frequent updates that must be sent to the PSAP regularly — usually daily, at a minimum. Several specialized applications vendors have developed such “third-party” solutions and are evolving them to operate correctly in the IP world. The PBX vendors have incorporated these systems into their phone system offerings. And almost all the vendor sites have information regarding how they handle 911. In addition, several states and municipalities have laws regarding how location information is to be captured and passed on appropriately and how frequently.

VoIP increases the mobility of users, who can simply unplug their IP-phone and plug it into another Ethernet jack anywhere inside the building, even remotely in a hotel or meeting room, via an IP-VPN and a broadband connection, while traveling or at another enterprise location. Wireless mobility, soft phones and voice over Wi-Fi phones further expands the ease of mobility and adds further complexity to the E911 implementation.

Enterprise IT or telecom departments must make sure, as part of their vendor selection processes, that the 911 issue is adequately addressed, that state and local laws are supported and that “off-campus” connections can be handled correctly. You certainly don't want a traveler in a hotel room, on their soft- or Wi-Fi-phone, connected via your VPN to your network, to have an emergency, dial 911 and have the call answered by the PSAP covering your headquarters location.

Thorough planning, researching of available solutions, asking questions of your potential vendors or resellers, your service or hosting provider, or your consultant or systems integrator as part of the decision-making process can avoid such an embarrassment and might even save a life.

David Yedwab is executive vice president of The Eastern Management Group and manager of the firm's public and private networking practices.