Type of Change:
With any Area Code relief being done by an NPA overlay, Bell Atlantic plans to convert 911 Trunk signaling from Multi Frequency to SS7. The purpose of this conversion is to reduce the addition of a second trunk group from the end
office to the 911 tandem in central offices that will have codes in both the existing and the proposed overlay code. With the implementation of SS7 for the end office to 911 tandem trunking, an Operators Services Tandem (TOPS) pass through will also be implemented to ensure the completion of a 911 call in the event of an SS7 failure. Bell Atlantic disclosed these changes for Pennsylvania in January, 1999.
Date Changes are to occur:
These changes will be completely implemented by the time of the activation of any overlay NPA relief. See Bell Atlantic web site http://www.bell-atl.com/areacode for current Overlay Area code relief in your areas of operation.
Location Change is to occur:
Entire Bell Atlantic region with the exception of the state of New Jersey.
Competitive Carrier Requirements:
It is the competitive carrier's discretion as to weather they convert existing 911 trunk groups to SS7. However, it is recommended that if a carrier has NXX codes in both the existing NPA and the proposed overlay, that they implement SS7 on these 911 trunk groups to avoid implementation of a second trunk group for the overlay NPA.
All competitive carriers who want to provide 911 from their switches to Bell Atlantic 911 Tandems via SS7 and do not contract for Bell Atlantic Operator Services, may want to consider provisioning an Operators Services Tandem (TOPS) pass through trunk group from Bell Atlantic for SS7 failure on 911. If the carrier does not want to obtain Bell Atlantic Operators Services Tandem (TOPS) pass through, they may want to approach their Operator Services Contractor to obtain equivalent services.
Reasonably Foreseeable Impact of Changes:
1.) The completion time for a 911 call will be reduced from approximately six seconds to approximately three seconds.
2.) In the traditional Multi - Frequency signaling environment, NPA identification takes place on the incoming trunk group at the 911 tandem switch. This requires that each NPA have its own group to the 911 tandem switch. With the implementation of SS7 on 911 trunk groups, NPA identification occurs with the SS7 signaling. As a result, there will be no need for separate trunk groups for NPA identification at the 911 tandem.
3.) For those carriers that implement SS7 for 911, there will be an increase in risk using SS7 for the completion of 911 calls. This risk increase is brought about by the possible failure of SS7 at the originating central office. To offset the increased risk of using SS7 for a 911 call, an alternate MF signaling path for 911 call completion will be provided by an Operators Services Tandem (TOPS) pass through to the 911 Tandem. In the case of an SS7 failure, the 911 call will be alternate routed to the Bell Atlantic TOPS switch. There will be no Operator intervention with this call.
For more information contact:
John A. Guthmann
Specialist - E911 Bell Atlantic - South
13100 Columbia Pike
Silver Spring, Maryland 20904
(301) 236 - 8372