Frequently Asked Questions

Question 1

What is Basic 9-1-1 service?

Accepted Answer

Basic 9-1-1 service is an emergency telephone system which automatically connects wireless 9-1-1 calls to a designated 9-1-1 Communications Center. Basic 9-1-1 may or may not provide the wireless phone’s 10-digit call-back number and estimated location. The handset must have battery power and be in a coverage area to complete a 9-1-1 call.

Question 2

What is Enhanced 9-1-1 Phase I service?

Accepted Answer

Enhanced 9-1-1 Phase I service is the first step in providing better emergency response service to wireless 9-1-1 callers. Public Safety/9-1-1 Communications Centers need to send a letter to T-Mobile requesting Phase I service deployment at their agency. Once Phase I service has been implemented, when a wireless 9-1-1 call comes into the 9-1-1 Communications Center (also called a Public Safety Answering Point or PSAP), the call-taker's computer screen will show the wireless phone's 10-digit call-back number if one has been assigned to the calling handset. In the event the wireless phone call is dropped, the call-taker may contact the caller. Phase I service also identifies the cell site/sector location information that the call was originated on to the call-taker's computer screen. This provides the call-taker with a general location (i.e. within the site coverage area) of the caller. The handset must have battery power and be in a coverage area to complete a 9-1-1 call.

Question 3

What is Enhanced 9-1-1 Phase II service?

Accepted Answer

Public Safety/9-1-1 Communications Centers need to send a letter to T-Mobile requesting Phase II service deployment at their agency. With Phase II service, the location information that is provided to the 9-1-1 Communications Center is the approximate X, Y (longitude, latitude) location of the handset making the 9-1-1 call. This location information is typically more accurate than the Phase I location information (cell site/sector). As with Phase I, Phase II service allows call-takers to receive both the caller's wireless phone number and their estimated location information. Since early 2004, T-Mobile has been deploying Phase II services. T-Mobile utilizes a hybrid solution, referred to as U-TDOA, Uplink-Time Difference of Arrival and AGPS, Assisted Global Positioning System, to provide an estimated Phase II location to the 9-1-1 Communications Center. The handset must have battery power and be in a coverage area to complete a 9-1-1 call.

Question 4

What is Text to 9-1-1 service?

Accepted Answer

Placing a voice call to 9-1-1 is your best option during an emergency. At this time, some 9-1-1 Centers are able to receive and/or respond to text messages sent to 9-1-1 via a T-Mobile handset. If a customer attempts to send a text to 9-1-1 in an area where the service is not available, an auto-reply message will be sent to the handset stating: “Please make a voice call to 911. There is no text service to 911 available at this time in this area. This is a free message.” T-Mobile entered into a voluntary agreement to begin the deployment of Text to 9-1-1 service starting in mid-2014. Public Safety/9-1-1 Communications Centers will need to send a letter to T-Mobile requesting Text to 9-1-1 service deployment at their agency once they are ready to receive text messaging. Please note, making a voice call to 9-1-1 is still the most efficient way to contact emergency services.

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