Until recently, voice information was carried only over a network dedicated to the voice information, such as a public switched telephone network (PSTN). Presently, however, other technologies have been developed that enable voice to be carried via a variety of networks that are not exclusively dedicated to the transfer of voice information. One of these technologies is Internet telephony, also called voice over internet protocol telephony (VoIP). VoIP contains technologies that enable voice to be carried via a data network of the Internet. In a VoIP system, the analog signals from the voice of a caller are converted into digital signals by a VoIP device before being transmitted through a gateway. The gateway then routes the signals over the PSTN dependent on the setup of the VoIP provider. The digitized, voice signals accordingly travel as discrete packets over a public or private Internet. This saves costs over a conventional PSTN as there is no toll charge when making a call.
However, various problems exist with VoIP systems. One of these problems is determination of the location of a caller for purposes of emergency (medical, police, fire) assistance. To access emergency assistance, a caller dials 911 in the United States or Canada and is connected to a Public Safety Answering Point (PSAP). The PSAP is one or more entities that receives emergency calls and dispatches the appropriate emergency services, if necessary. As the basic emergency phone number is the same throughout the United States and Canada, the call is transmitted to one or more routers in a PSTN network of routers through a PSTN gateway to determine the appropriate PSAP to respond to the emergency call, that is, the PSAP most proximate physically to the caller. The appropriate PSAP is determined by using an Automatic Location Identification (ALI) database that associates telephone numbers with street addresses and local emergency response. Once the address is determined, it is transmitted to a display for the benefit of the emergency response personnel. Emergency services then react to a 911 call using the location of the caller.
When using a conventional non-portable telephone, the location of the telephone is known and registered as a particular location. However, the information used to route a VoIP call may not be sufficient to determine the location of the VoIP caller. Unlike fixed telephones, which each use a dedicated switch to connect to the PSTN network, a VoIP network uses one switch to serve multiple VoIP devices distributed over a broad geographic area. Moreover, VoIP devices are nomadic, that is, VoIP phones can be transported to any location where a network connection is available, connected to the Internet, and calls may be made from the new location. Thus, there is no fixed relationship between the location of a caller using a VoIP device and the phone number used by the VoIP device. Nor do VoIP networks generally provide information regarding the location of callers.
Thus, there is a need for a VoIP device and associated method in which emergency calls are routed to a proper emergency service provider for providing appropriate emergency response to the caller.