Geographic Portability and 9-1-1

Issue paper for Midwest Region LNP steering committee

Submitted by Illinois chapter of NENA

The enhanced 9-1-1 systems currently in place would need some major changes within network architecture and database processing, in order to continue to function correctly in a geographic portability environment.

Enhanced 9-1-1 allows for the delivery of a 9-1-1 call to the correct public safety answering point (PSAP) with the callerís phone number and address used for that routing and delivered to that PSAP.

In the event of an error in the 9-1-1 system, in which the phone number and/or the address cannot be found or is garbled, a default routing procedure is in place, ensuring that the call still goes to a PSAP capable of correctly processing the reported emergency.


The network would need changes in order to correctly process 9-1-1 calls and retain those features associated with enhanced 9-1-1.

At least one of the 9-1-1 selective routers in place in northeast Illinois can handle no additional area codes. It, like other similar routers in place in parts of Illinois and some other areas of the country, can only handle four area codes. Any such routers would need upgrading if available, or replacement. Cost estimates for such work would need to be provided by the switch vendor and/or the 9-1-1 service provider utilizing such equipment.

Warranting further study is the potential need to change the existing 9-1-1 network to SS7 technology, if geographic portability is implemented. Such a change would allow the routing and transferring of 9-1-1 calls over a much greater area, and would also almost totally eliminate 9-1-1 calls with ANI (automatic number identification) failure. In Illinois, such a change would require further action by the Illinois Commerce Commission, which has been hesitant to approve its use beyond the city of Chicago.


Accurate and timely data is essential to the correct functioning of an enhanced 9-1-1 system. When 9-1-1 is dialed by a caller wishing to report a fire, medical and/or police emergency, the phone number of the caller is found in a 9-1-1 routing database, which provides the pointer to the correct PSAP.



Illinois NENA geographic portability paper, 071799

That pointer had been determined when the callerís customer address record was processed into another 9-1-1 database (called an MSAG, master street address guide), which assigns the pointer based on address range assignments. This occurred sometime, hopefully shortly, after the customerís phone service originally began with the local service provider.

If that process was successful, the callerís customer address record was also inserted into a third 9-1-1 database (ALI, address location identification), which is used for providing a call taker with the customerís name, address and emergency services response agencies (police, fire and medical) when a 9-1-1 call is answered at a PSAP.

The accuracy, timeliness, and synchronization of the above three 9-1-1 databases is extremely important to the correct functioning of an enhanced 9-1-1 system.

When a customerís new service is started with a local provider, the 9-1-1 data processing currently begins after initial dial tone is provided. That processing, barring any problems such as incorrect information, usually takes between four and 72 hours, dependent on which company is handling the 9-1-1 database processing.

The industryís fine tuning of local number portability processes appears to have created a delay in 9-1-1 database processing that has just been found in recent months.

For LNP, to ensure that local customerís porting from one provider to another did not temporarily lose enhanced 9-1-1 service; a special 9-1-1 database processing was begun throughout the country.

Prior to LNP, if a customer changed local phone service (and therefore changed phone numbers), the original 9-1-1 database record was deleted and a new one was added. The two were not processed sequentially. The speed of 9-1-1 database changing was determined by the submission of data from the new local service provider and the timeliness of the 9-1-1 database providerís updates.

With a LNP, a sequential process was invented. The donor service provider would send an "unlock" order through, after completion of the porting, and the recipient service provider would send a "migrate" order through which would overwrite the existing 9-1-1 database record. The "unlock" was determined to be needed for security reasons. The process ensured that a customerís information stayed in the 9-1-1 database during the porting process.

To account for customers who are both porting and moving location (within a rate center) the process was altered, allowing the donor service provider to send a "delete" order through, and the recipient service provider to continue to send a "migrate" order.



Illinois NENA geographic portability paper, 071799

These two orders need to be done sequentially and it has been determined (by the 9-1-1 community at least) that they should be done, if at all possible, on the first day of customer service at the new location.

However, the LNP side of the telephone industry appears to have modified its processing in order to ensure no loss of dial tone by a customer, utilizing a procedure that extends the 9-1-1 database processing an additional 24 hours at least.

It appears at least some of the industry is following an LNP process flow that has the donor service provider process itís disconnect orders the day after the recipient provider processes its connect orders.

The disconnect order completion of the donor service provider is what is used by the 9-1-1 side of the company to send through an "unlock" or a "delete" order to the 9-1-1 database.

Until that order is sent through, the recipient service providerís new customer record (the "migrate" order) is not processed. If it contains a new address for the customer, it still must wait at least 24 hours longer because of the disconnect delay.

It appears that some LNP processes today can contribute to wrong information being in the 9-1-1 databases for at least several hours and possibly days. This can contribute to the mishandling of 9-1-1 emergency calls, particularly in the first minutes, which are critical if involving fire, medical and/or law enforcement life-threatening incidences.

These errors center on a customer moving only within a rate center. Except in those few areas of the country which are involved in very large multi-county rate center consolidations, these are still short distances and usually within the same PSAP area or at most, a neighboring PSAPís jurisdiction.

With geographic portability, the distances can be much, much greater, and so the 9-1-1 databasesí accuracy involving a customerís phone number and address, must be as close to 100 per cent as possible.

For the 9-1-1 database process to work correctly in an area with geographic portability, the timeliness, accuracy and synchronization should be done at least as well as the regional number portability database and service provider SMS coordination.

Rather than processing 9-1-1 database service orders after dial tone is provided, they should be checked for accuracy (such as MSAG validation) prior to dial tone.





Illinois NENA geographic portability paper, 071799

The actual insertion of the pointer record into the 9-1-1 routing database and the customer name/address record into the 9-1-1 ALI database should be done at the same time as dial tone is provided from the new service provider as evidenced in the regional number portability database. The two 9-1-1 databases should be closely coordinated and synchronized within minutes of dial tone changing (not several hours or multiple days later).

Currently, there is at least one competitive local service provider sending through its 9-1-1 database record orders triggered on its phone number changes/additions to the appropriate regional number portability database.

Currently, there is at least one incumbent service provider in one state, that is processing 9-1-1 record changes once per hour, 24 hours a day, seven days a week, for both its customers and for any competitive service providers in that area.

In summary, geographic portability requires 9-1-1 network changes so that selective routers can handle more than four area codes, so that ANI failures are reduced to near zero, and so that much larger areas can pass and route 9-1-1 calls.

It requires changes to the 9-1-1 database processing flow, so that the appropriate 9-1-1 records are added or changed within a few minutes of dial tone provisioning, possibly automatically triggering such actions from addition/change completions within the regional number portability database.

Respectfully submitted

Illinois chapter, NENA (National Emergency Number Association)

Prepared by Rick Jones, ENP

IL NENA vice-president

Loves Park 9-1-1

540 Loves Park Drive

Loves Park, IL 61111

office 815-654-5011

fax 815-633-0555









Illinois NENA geographic portability paper, 071799