E9-1-1 for Legacy Premise-based MLTS
Incumbent Local Exchange Carriers (ILEC) can provide the basic necessities that are required to support E9-1-1 for MLTS.15 For PBX MLTS, the E9-1-1 solution is called `PS/ALI' and encompasses:
· Access to the PSTN through the provisioning of ISDN-PRI or Centralized Automatic Message Accounting (CAMA) circuits for call processing,
· Direct Inward Dialing (DID) numbers for telephone stations,
· Private Switch/Automatic Location Identification (PS/ALI) -- the establishing of an E9-1-1 database account so the MLTS owner can establish and maintain ALI records with the E9-1-1 System Service Provider's (SSP) E9-1-1 database,16 and
· PS/ALI maintenance for station additions, changes and deletions.
Circuits or Trunking requirements vary depending on whether the MLTS is digital or analog. For PBX systems that use digital trunks - Primary Rate Interface Integrated Services Digital Network (PRI-ISDN), the provisioning of PS/ALI may be accommodated without the requirement of dedicated trunks for transporting 9-1-1 calls. For PBX systems that use analog trunks (e.g., they are not compatible with PRI and/or PRI trunks are not available from local service providers), the provisioning of PS/ALI may be accommodated by using dedicated circuits that operate with the CAMA signaling protocol. There are two CAMA alternatives that can be implemented; connecting the circuit to the Selective Router or connecting the circuit to the Public Safety Answering Point (PSAP).17
DID numbers permit a caller outside the company to call an internal extension without the need to pass through a switchboard operator or attendant at the MLTS.18 DID numbers are critically important to the PSAP as the ANI19 for call-back purposes and for defining a more granular location (cubicle, room, building, floor, etc.) in the E9-1-1 database record. A DID for every telephone capable of dialing 9-1-1 is called a Station Level solution.
The PS/ALI Database contains a mapping of telephone numbers to elements of detailed information (building, floor, cubicle, etc.) and is used to record the location of emergency callers.20 CAMA and ISDN/PRI circuits do not have the ability to transmit location information. Location information is available only if it has been pre-populated in an E9-1-1 database and kept up-to-date by the MLTS Operator in advance of any emergency calls being dialed. The PS/ALI database is the primary source of information used by public safety officials to locate individuals during emergencies.
The providers of network services maintain the PS/ALI databases at the direction of local government. These may include ILEC, Competitive Local Exchange Carriers, or VoIP service providers. The carrier or service provider is responsible for accurate location information up to the point of the demarcation (demarc).21 From the demarc, the MLTS Operator/Manager has the responsibility for establishing and maintaining the MLTS with the required or desired level of location accuracy.22 The location of each telephone station must be identified in an ALI record created and sent for inclusion in the E9-1-1 database.
PS/ALI Maintenance is required as MLTS telephone stations are added, moved or changed. An ALI record for each MLTS Station affected must be sent to the E9-1-1 SSP DMS that reflects the new information or location. When an MLTS telephone number is disconnected and no longer in service, a delete record must be sent to the E9-1-1 SSP Database Management System to remove the record.23
The Operator/Manager or leadership of the organization who gains benefit from the services of an MLTS is ultimately responsible to ensure that the information contained in the PS/ALI database is accurate. However, it is not always clear whether it is the owner or the operator who is responsible for maintaining accurate PS/ALI database information, since they may be two different parties. When an MLTS system is privately owned, it is the Operator/Manager of the asset who is responsible. But, there are also cases where an organization may use the services of an MLTS, but not own the asset. An example of this is the case in which an organization receives MLTS services on a contractual basis from a third-party. In this case, the Operator/Manager of the organization receiving the service has the ultimate responsibility to ensure accuracy of the location information in the PS/ALI database for the end-users of the services provided by the MLTS.24
Some PBX environments present more complex challenges. The PS/ALI service may not be able to accommodate off-premises extension lines, for instance, if the extension lines are terminated at locations outside the geographic area served by the 9-1-1 selective router. In very large PBX system configurations, there may be multiple PBX switches and/or remote modules that are networked to serve multiple locations with a common numbering plan using DID numbers out of the same NPA/NXX.25 These unique situations must be dealt with on a case-by-case basis with the participation of the PBX vendor, the dial-tone provider, the 9-1-1 SSP and the local 9-1-1 agency.26
15 First, manufacturers must provide PBXs with direct inward dialing (DID) to support MLTS signaling through such systems as Centralized Automatic Message Accounting (CAMA) 209 or Integrated Services Digital Network (ISDN)210 interfaces in order to deliver the calling number identification that makes MLTS E9-1-1 possible. Both CAMA and ISDN are well-known, readily available technologies, the availability of which would be unaffected by a change to Part 68. [Part 68 of the FCC rules governs the connection of private line termination equipment to the Public Switched Telephone Network (PSTN).] Assuming an MLTS operator has an MLTS compatible PBX, any carrier involved must provide trunking and interfaces capable of transferring location information received from the MLTS. However, the MLTS operators must transmit this location data, and also must populate (and update) the ALI database to provide specific geographic cross references to the transmitted data for the PSAP to receive. Finally, PSAPs must have the capability to receive this information. A general requirement in Part 68 that MLTS be E9-1-1 compatible would not contribute to this process. (FCC 03-290, Report and Further Notice of Proposed Rulemaking CC Docket # 94-102, 2003.)
16 AT&T California and Verizon California are the 9-1-1 SSPs within their respective footprints and operate the Database Management System (DMS) used to maintain the 9-1-1 database.
17 NENA 03-502 at 1.
18 NENA Master Glossary of 911 Terminology, NENA-01-002.
19 Automatic Number Identification (ANI).
20 NENA 06-502 at 10.
21 The point at which telephone company maintained equipment and wiring terminates at the customer's premises. GO 133, section 1.3.
22 Id. at 12.
23 NENA 06-003 at 9.
24 NENA 06-502 at 10.
25 NPA refers to the Numbering Plan Area commonly known as the area code, and NXX refers to the exchange, which is the three digits following the area code.
26 NENA 03-502 at 8.
