Number Portability and the Wireless Carriers

Washington NENA Technical Subcommittee Bulletin – December 1997

CAD & Mapping Update

Submitted by Allen Jakobitz 360-923-4515

Maps are extremely important to telecommunicators in PSAPs. They are frequently used to help locate callers or incidents. Maps can be critical in the dispatching of responders.

There are some CADs that have proprietary mapping integrated in their systems, like Logisys and Intergraph. Kitsap (CENCOM) and Franklin are using Intergraph. Jefferson and Kirkland are using Logisys. Some PSAPs view electronic maps peripherally to their CAD, like Klickitat, Wahkiakum and Island (I-COM).

The FCC has ruled that wireless companies must be able to provide latitude and longitude coordinates to PSAPs by 2001. Many PSAPs have seen this as an opportunity to prepare for changing technology by initiating talks with their GIS departments. This foresight will be rewarded by building necessary communication channels now that will enable electronic maps to be kept accurate. Mason has recently invited all agencies to discuss how they can best avoid duplication and share data with one another.

Electronic map viewing in the PSAP doesn’t have to be expensive. Spokane is creating software that will become public domain. It should be ready for review first quarter of 1998.

There is a PSAP mapping forum that meets irregularly. If you wish to receive PSAP mapping information, send an email to [email protected].

FCC Docket 94-102 Update

Submitted by Jane Bissonnette 206-674-1030

The FCC Reconsideration (or appeal) of the Report has been completed. While the full and complete text is not yet public, they did issue statements that indicate their policy positions on the following issues:

1) The deadlines for both Phase I and Phase II are reinforced and fully confirmed. There are no changes to the April 1, 1998 deadline for Phase I or the Oct. 1, 2001 deadline for Phase II.

2) All calls–including non service initialized handsets — must be transferred to the PSAP and PSAPs can no longer decide for themselves whether to receive them. (Previously, each PSAP could chose).

3) Wireless carriers will not be granted waivers easily if the LEC cannot do Feature Group D in a given market by the required deadlines–if the wireless carrier has other options available on the market.

4) The FCC said they fully intend for the Report to be completely “technology neutral” so as not to favor or disadvantage either LEC or non-LEC affiliated solutions.

5) There is a temporary suspension of the TTY requirements under the Report for equipment for the deaf until technical obstacles can be resolved.


Submitted by Lynn Mell 206-674-1006

The CTIA (Cellular Telecommunications Industry Association) forum “Seeking Solutions to TTY/TDD Through Wireless Digital Systems” was held on September 17-19, 1997 in Arlington, VA. The forum included presentations from the wireless industry, the deaf community, subject matter experts, and equipment and services providers. All presentations shared the common thread of interdependence among the participants. The consumer perspective encouraged finding solutions that not only support technical requirements but user requirements. Industry presentations provided overviews of current and proposed technology solutions related to TDD/TTY services. The 9-1-1 service providers and equipment manufacturers addressed issues related to providing service today and in the future with a call to the interest groups to ensure workable, acceptable solutions. The ultimate goal is to provide TTY service in a digital air environment.

The FCC mandate requires wireless carriers to be capable of transmitting 9-1-1 calls made through the use of TTY equipment. However, due to the technical issues involved with TTY, the FCC has issued a temporary suspension of the TTY requirement until technical obstacles can be resolved. Representatives at the forum discussed and agreed that “There is a petition to extend the compliance date for 18 months. This group, consisting of representatives from the four interest groups and dedicated to working together, found there was no disagreement that more time is needed to find the best solution for TDD users.” The group further found that continued intensive collaborative efforts are required. The request for an extension of time was agreed to be for no longer than 18 months. Three working groups were established to address the near-term and long-term solutions: Performance of TTY Signals over Voice Service, Performance of TTY Signals over Data Service, and a Coupling Work Group. The next forum meeting is set for December 11-12, 1997 in Washington, DC. For more information on the meeting, contact Janette Stout at 202-735-3224.

Number Portability and the Wireless Carriers

Submitted by Jane Bissonnette 206-674-1030

In the first Report and Order on Telephone Number Portability, the FCC required all covered wireless carriers to develop and implement the capability to deliver calls from their networks to ported numbers anywhere in the US by 12/31/98. By 6/30/99, wireless service providers must offer service provider portability, including the ability to support roaming throughout their networks. In a reconsideration order released 3/6/97, the FCC state that wireless service providers need only deploy service provider portability in the largest 100 metropolitan statistical area in which they have received a specific request by 9/30/98. Local exchange carriers are mandated to provide the service by 3/31/98.

The FCC defines number portability in three parts:

  1. Service provider portability – this is the only type required by the FCC at this time. Service provider portability allows a customer to change service providers and still keep the same telephone number. The change is limited in geography to a specific rate center. Changing wireline to wireless service providers qualifies as a change in service provider and is within the scope of the recent order.
  2. Location portability – this is the ability to change service providers from one location to another without having to change a telephone number.
  3. Service portability – this is the ability to change telecommunications services such as switching from basic telephone service to ISDN while retaining the same phone number.

The basic architecture for number portability was recently depicted in the September 15, 1997 issue of Telephony. The architecture involves the use of the Advanced Intelligent Network. It works as follows:

Number Portability Call Flow

  • Caller A wants to place a call to Caller B who is ported (they have changed service providers but retained their telephone number)
  • Caller A’s serving switch analyzes the dialed digits, recognizes them as a ported number and forwards a query through the Advanced Intelligent Network via the Signalling Transfer Point to the Service Control Point.
  • The Service Control Point determines the location routing number for the dialed digits and returns this information to the originating switch via the Signalling Transfer Point. Note that the Service Control Point receives real-time updates of ported number information from the administration center.
  • The originating switch receives the routing information and forwards the call to the recipient switch based upon the location routing number.
  • Note: In some cases the originating switch may not have the intelligence to recognize the ported number, in this case the call is routed to the “donor” switch. The donor switch is the switch that the customer had the service from originally. In this case the donor switch originates the query to the Advanced Intelligent Network and the query is returned to the donor switch and the donor switch forwards the call to the recipient switch.

In this diagram the wireless carrier can have the intelligence in their own network, where their originating switch has the intelligence to query their own data base or they can contract with a Local Exchange Carrier (which is the donor switch scenario) to supply the database maintenance. Either way there’s a lot of work to do to solve this very complex problem.

The Washington NENA Technology Subcommittee will have a teleconference on

January 13th (Tuesday) at 10:30am. Call in number is 206-205-0999.