how 911 service works with Voice over IP

Canadian Radio-television and Telecommunications Commission (CRTC) classified VoIP services into three categories: Fixed, Nomadic, and Foreign Exchange. However, Fixed and Foreign Exchange services have same features. Fixed VoIP service can also be called “Fixed/native” service and Foreign VoIP service can also be named “Fixed/non-native” service according to the CRTC. Users of Fixed and Foreign Exchange VoIP service can only make a call from where they are being served and registered to use the VoIP services. If they just move their VoIP devices to somewhere else not registered without confirming with the service providers, and then connect the devices to network that associates with the internet, VoIP calls cannot be made because Fixed and Foreign Exchange service are working on fixed-oriented environment. However, there exists a decisive difference between the two services. Canadian carriers providing Fixed VoIP services assign an end-user an NXX-NXX (e.g in Toronto 416-588) number that matches any of the local exchanges. In other words, Fixed VoIP users in Toronto are allowed to only have Toronto area code associated with any exchange number within Toronto. On the other hand, Canadian carriers offering Foreign Exchange VoIP services allow users to have another area code number with exchange number. For example, a user located in Toronto with Ottawa local telephone number can exist.

There are two types of 911service, Basic 911 and Enhanced 911. In basic 911 service, dialed 911 calls route to assigned Public Safety Answering Point (PSAP)s, which is a “specialized answer-call center” responsible for all 911 calls dialing within a specific area  covered by the PSAP. While a trained agent of PSAPs answers a 911 call, he/she receives just the caller’s phone number not location information. And then the agent routes the call to emergency center such as police, firefighting, and ambulance service. If the caller is not in condition to communicate or has language barrier, the call will not be routed properly. On the other hand, In enhanced 911 service, when a user dials the number 911, the call is directed to the customer's serving PSAP and an agent of PSAP automatically get the customer's location information and phone number which is available from ALI(Automatic Location Information) database provided by Incumbent Local Exchange Carrier(ILEC). And the agent of PSAP routes the call to police station, fire fighting department, or emergency ambulance service even the caller is not able to communicate with the agent.

      Technology for 911service was originally developed for conventional Public Switched Telephone Network (PSTN) in which telephones remain at a fixed location. When implementing of 911 service in VoIP environment is decided by CRTC, VoIP providers encountered some technical challenges that is how to identify the caller’s location when a 911 call is made from a VoIP phone, which is not remained fixed at a specific place because VoIP technology is based on the worldwide internet and eliminated geographic limitation while traditional voice phones operates based on a specific geographic area. However, due to Fixed VoIP service resembles traditional voice phone, Fixed VoIP carriers should provide same level of 911service either Basic 911 or Enhanced 911, which is provided by ILEC. When a Fixed VoIP customer places a call from a fixed address within an “ILEC-defined exchange area” with phone number corresponding to the exchange (e.g. 416/647-NXX in Toronto) then the 911 service will operate in same situation as traditional phone service does. If a Foreign Exchange VoIP customer makes a 911 call from a fixed location but not covered by the customers PSAP due to the customer’s exchange number does not belong to the PSAP, the call will be routed to an incorrect PSAP and traditional 911 service would not function properly. Therefore, interim 911 service should be provided to customers who are served by FX VoIP service providers. When a customer places a call, the call is routed to a call-center which is operated by the service providers. A trained receptionist answers the phone and receives the ALI and ANI(Automatic Numbering Identification) information together and then redirects the call to the customer’s designated PSAP with the populated information containing the customer’s location and phone number. In this scenario, the 911 service call will operate in the same manner as conventional telephone does.