The troubles Vonage and other VoIP providers have been going through over whether they provide E911 services to their customers pose similar problems to enterprises, though many corporate phone managers are unaware of them.The problem - that there is no automatic way for the police\/fire\/medical dispatcher to know where the phone call is coming from - is one that has been present in many corporate phone networks for years, though for a variety of reasons, it has never become a raging issue, according to experts speaking at the Internet Telephony conference.Highly publicized cases of residential VoIP customers dialing 911 to report a burglar in the house and getting a recorded message that they had to pay extra for 911 service prompted the FCC last year to order VoIP providers to provide E911 service. VoIP service providers are still working toward achieving that.The problem stems from the nature of the phone system. With traditional residential phones, one phone number represented one location. A database of what number corresponded to what home told dispatchers where the caller was located. So if a heart attack victim had the strength to dial 911 then passed out, the dispatcher could still send help.With VoIP over broadband services, the phone could be anywhere because it can work from any Internet connection. It is identified to the network only by IP address, not location. To be useful, a location database of movable phones would require users to reliably update where they are, something unlikely to happen, according to Bob Chrostowski, a representative of VoIP vendor Iwatsu Voice Networks who moderated a session on E911.If the heart attack victim dialed 911 on a VoIP phone then passed out, what happens depends on the service. The call could go nowhere because the service doesn't recognize 911 as a number to connect. The call could be routed to the wrong public safety answering point (PSAP) the local call center that handles 911 calls. Or it could reach a person at a national call center who is supposed to query the caller about their location and transfer them to the right PSAP. Or the call could go to the PSAP nearest the last address entered in the location database by the VoIP customer. The accuracy of that address is uncertain, Chrostowski says.Vendors are working on means to put global positioning functionality in VoIP phones, but these are not yet available.In enterprises with traditional PBXs a similar problem can exist. A sprawling corporate site may have just one phone number, with callers prompted to seek then dial the correct extension. A 911 call from such a site could tell the 911 dispatcher the address, but the address might contain many buildings housing hundreds of employees. Finding the victim would be difficult.Depending on local laws, businesses may be required to map phone extensions to individual offices or to zones of modest size within vast corporate sites, says Robert Aldrich, an attorney with Dickstein, Shapiro Morin & Oshinsky in Washington, D.C., who specializes in telecommunications law. But that would only work if each phone had its own direct inward dial (DID) phone number that the public phone switch could discern and only if the business kept its map of where each phone is located up to date, he says.When telecom technicians move traditional PBX phones, they may or may not update these locator databases, he says.He says he knows of no case in which someone sued a business for failing to keep its database updated, but the possibility exists.Failure to update the database is even more of a problem with VoIP in corporate settings because employees can move the phone themselves by simply unplugging it from the network and plugging it back in again anywhere else there is a free Ethernet jack. End users are less likely to remember or even know there is such a database he says.The problem is compounded with VoIP over Wi-Fi, where the phones are mobile and users move from place to place without having to plug the phone into anything. Some vendors are working on Wi-Fi triangulation schemes that would locate a Wi-Fi handset within a certain distance, but these are not available on commercial phones, says Matt Wilson, senior product manager for Intrado, a 911 service provider.