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E911 Enhanced MF Signaling (with an excellent description of how ANI and ANI-II are transmitted with MF tones)


                          for the implementation of
                            Enhanced MF Signaling,
                            E9-1-1 Tandem to PSAP

NENA Technical Reference

NENA 03-00X Draft 4, March 12, 1997

Recommendation for Enhanced MF Signaling,

E9-1-1 Tandem to E9-1-1 PSAP

Prepared by:

National Emergency Number Association (NENA)

Network Technical Committee

Published by:


Printed in U.S.A.


                             TECHNICAL REFERENCE


This Technical Reference is published by the National Emergency Number
Association (NENA) as a guide and recommendation for designers and
manufacturers of Enhanced 9-1-1 selective routing tandems and customer
premise systems. It is not intended to provide complete design specifications
or parameters, nor to assure the quality of performance of such equipment.

NENA reserves the right to revise this Technical Reference for any reason,
including but not limited to, conformity with criteria or standards
promulgated by various agencies, utilization of advances in the state of the
technical arts or to reflect changes in the design of equipment for services
described therein.

It is possible that certain advances in technology will precede these
revisions. Therefore, this Technical Reference should not be the only source
of information used to purchase selective routing tandems, customer premises
equipment and/or Feature Group D protocol functionality for either. NENA
members are urged to contact their local telephone company representative to
ensure compatibility with the Telco network.

The techniques and equipment characteristics disclosed herein may be covered
by patents held by individuals or corporations. No license, expressed or
implied, is hereby granted. This document is no to be construed as a
suggestion to any manufacturer to modify its products, nor does this document
represent any commitment by NENA or any affiliate thereof to purchase any
product whether or not it provides the described characteristics.

This document has been prepared solely for the voluntary use of E9-1-1
service providers, E9-1-1 equipment vendors, and participating telephone
companies. It recommends the use of a specific technology for specific
purposes. This document does not automatically exclude the use of any other
technologies to provide similar or equivalent services.

By using this document, the user agrees that NENA will have no liability for
any consequential, incidental, special, or punitive damages that may result.

This document has been developed by the NENA Network Technical Committee. The
NENA executive board has recommended this document for industry acceptance.
Recommendations for change to this document may be submitted to:

National Emergency Number Association

Attention: Executive Director

11 South 6th Street

Coshocton, Ohio 43812


1.1 General

This NENA Technical Reference defines the use of Feature Group D signaling
protocol between the E9-1-1 selective routing tandem and E9-1-1 customer
premise equipment (CPE).

1.2 Purpose and Scope of Document

This Technical Reference is a guide for designers and manufacturers of
selective routing tandems and PSAP CPE. It may also be of value to
purchasers, maintainers and users of such equipment.

This document describes the use of Feature Group D (FGD) protocol in place of
the protocol described in Bellcore Technical Reference TR-TSY-000350. It does
not recommend any changes to , or the replacement of, in-place multi-
frequency (MF) signaling used between the E9-1-1 selective routing tandem and
the E9-1-1 PSAP CPE. Nor does this document recommend any other modifications
to selective routing tandems or CPE, beyond those necessary to implement the
Feature Group D protocol.

The purpose of utilizing Feature Group D is to facilitate the delivery of one
or two ten-digit ANI transmissions to the PSAP. The protocol supports both.

The existing protocol, as described in Bellcore TR-TSY-000350, limits the
PSAP to receiving 9-1-1 calls from callers in up to four area codes only. The
implementation of FGD removes that limitation by delivering all ten digits of
the caller’s telephone number.

FGD also provides for the delivery of two ten-digit numbers to the PSAP. This
capability (delivery of two ten digit numbers) is required to implement Phase
1 of FCC Report and Order 96-264(?), the delivery of a wireless 9-1-1
callers ten digit callback number plus a ten digit number that identifies the
cell/sector through which the call originated.

1.3 Organization of Document

The document is organized into four major sections:

Section 1 - Introduction

Section 2 - Call Progress Signals

Section 3 - Trunk Maintenance Test Calls

Section 4 - Database Query Protocol

Section 5 - References

1.4 Reason for Reissue

NENA reserves the right to modify the Technical Reference. Whenever it is
reissued, the reason(s) will be provided in this paragraph.


2.1 E9-1-1 PSAP to Tandem with 10/20 Digit ANI via Feature Group D Signaling

MF outpulsing is required to send ANI to the E9-1-1 PSAP. An idle 9-1-1 trunk
to the PSAP is seized and an attempt is made to seize and connect an idle MF
transmitter to the outgoing 9-1-1 trunk. When an MF transmitter is available,
it is seized and connected to an E9-1-1 outgoing trunk to the PSAP. Standard,
start-dial timing is done for receipt of the ANI start signal (approximately
250 +50 ms wink signal) from the PSAP CPE. There are several failure modes
that can occur after the E9-1-1 tandem seizes a dedicated E9-1-1 outgoing
trunk and connects an MF transmitter.

The normal sequence of events that occurs after a 9-1-1 trunk seizure is
described below. Failure modes are discussed as they are applicable to a
particular sequence.

(Sections 1-3 following are reprinted verbatim from NENA Technical Reference
NENA-04-001, Generic Standards for E9-1-1 PSAP Equipment, dated June 20,
1996. Sections 4 and 5 have been taken from NENA-04-001 but modified to
address the differences and requirements of the FGD type protocol.)

     1. The E9-1-1 tandem office sends an off-hook signal to the PSAP
     indicating 9-1-1 trunk seizure.

     2. The E9-1-1 tandem office waits 4 to 20 seconds for receipt of the ANI
     start pulsing wink from the PSAP. The normal call sequence continues if
     the PSAP returns the outpulsing wink signal. If the start pulsing wink
     signal is not received within 4 to 20 seconds, the E9-1-1 tandem office
     puts the trunk on the trunk maintenance list and makes one retry on a
     different E9-1-1 trunk to the PSAP. In this case, the trunk hunting and
     the connection phase begin again.

     3. When the PSAP recognizes the E9-1-1 trunk seizure, it shall return an
     ANI start pulsing wink signal (250+50 ms Line Reversal) to the E9-1-1
     tandem within 4 seconds. After sending the start pulsing wink signal, if
     the MF pulses are not received within 4 seconds, or garbled pulses are
     received, the PSAP completes the call as if an ANI failure has occurred.
     That is, the CPE shall immediately signal the attendant(s) and return
     audible ringing to the calling station via the E9-1-1 network. In this
     case, when the attendant answers, all zeros are displayed on the ANI
     display. Otherwise, receipt of the start pulsing wink signal typically
     causes the E9-1-1 tandem office to start MF outpulsing.

     4. The MF outpulsing consists of a stream of MF tone pulses, 53 ms to 65
     ms duration, separated by silent intervals of 55 ms to 65 ms. The ANI II
     and DN digits are preceded by a KP digit of 115 ms to 125 ms duration
     and followed by an STP digit of 55 to 65 ms duration when a single, ten
     digit ANI is transmitted, or an ST digit of 55 to 65 ms duration when
     two ten digit numbers are transmitted. (The KP, ST and STP digits are
     within the family of MF signals.) For transmission of a single, ten
     digit ANI, the E9-1-1 tandem begins MF outpulsing the ANI information to
     the PSAP in the form KP II NPA NXX YYYY STP. For transmission of two,
     ten digit numbers, MF outpulsing begins in the form KP II NPA NXX YYYY
     (calling party’s number) ST KP NPA NXX YYYY (dialed number or pseudo
     ANI) ST.

     The "II" represents encoded information indicating whether the calling
     line display device (ANI display) should remain steady or flash, or if
     the call is a test call. II digits will be used as follows:

     II Digit Meaning

     40 Steady ANI display

     44 Flashing ANI display

     48 Test call

     If a valid ANI is not available at the E9-1-1 tandem office, a
     fictitious NPA-NXX-YYYY ANI is sent to the PSAP as either 000-911-0000
     or 000-911-0TTT. The digits TTT indicate the E9-1-1 tandem switch
     Central Office number (also known as ESCO code) associated with the
     originating office.

     000-911-0TTT may be sent due to ANI failures, multi-party or QZ billing
     lines, and possibly a 9-1-1 call received via a message trunk.

     000-911-0000 is sent when an anonymous call is made to a PSAP. An
     anonymous call is a 7 or 10-digit call (non 9-1-1) to the DN of the PSAP
     (where applicable).

     Note: If an ANI failure occurs between the E9-1-1 tandem office and the
     PSAP, the digits that may be displayed are 000-000-0000.

     5. Upon receipt of the complete ANI information, the PSAP shall signal
     the attendant(s) and return audible ringing to the calling party. When
     the call is answered, the PSAP shall disconnect audible ringing, connect
     the call to the answering attendant, display the calling party’s number
     on the ANI display, and return an off-hook signal to the E9-1-1 tandem
     office, indicating that the call has been answered.

     If a single, ten digit ANI has been delivered with the call, the E9-1-1
     PSAP CPE will display the number on the ANI display and use that number
     to query the ALI database.

     In Phase 1 wireless implementations, when two, ten digit numbers have
     been delivered, the PSAP CPE will display the calling party's number on
     the ANI display, but use the pseudo ANI to query the ALI database.

     In Phase 2 wireless implementations, the calling party’s number may be
     used to query the ALI database, depending upon the configuration of the
     location determination technology (LDT) interface. In this instance, the
     pseudo ANI would only be used to query the ALI database in the event the
     calling party's number was garbled or not received.

     Calls originated from non-service-initialized wireless telephones will
     not have a calling party number to display. It is also conceivable that
     multiple calls from non-service-initialized wireless telephones could
     be received at the PSAP simultaneously. In this event, a "pseudo CPN"
     may be assigned by the MSC (possibly as a temporary local directory
     number, or TLDN). This pseudo CPN will be used to tie the x and y
     coordinates computed by the LDT system to the voice call, but may not be
     usable as a callback number.

     6. After the answer is detected, the E9-1-1 tandem office supervises the
     call for disconnect and a PSAP transfer request.

3.0 Trunk Maintenance Test Calls

     For a PSAP equipped with CPE for ANI display, test calls can be made
     from the E9-1-1 tandem office using encoded ANI. The PSAP CPE should
     decode the special ANI as a test call and connect the trunk under test
     to a test termination facility in the PSAP CPE. Specifically, when KP 48
     STP is outpulsed to the PSAP, the E9-1-1 trunk under test should be
     connected to a permanent busy circuit without answer supervision (no
     battery reversal) in the PSAP CPE. This allows the E9-1-1 tandem office
     to verify the integrity of the circuit using the trunk diagnostic
     program. The test call sequence is listed in the following three steps:

               1. After seizing the selected idle trunk and receiving the
               wink start signal prior to time-out, the E9-1-1 tandem office
               outpulses KP 48 STP to the PSAP.

               2. The PSAP should interpret the digits 4 and 8 as a
               maintenance test call and connect the incoming E9-1-1 trunk to
               a permanent busy tone (continuous 60-ipm, tone) without answer
               supervision (normal battery polarity). The tone should be
               returned to the E9-1-1 tandem office within 20 seconds after
               receipt of the wink start pulse, otherwise, the E9-1-1 tandem
               office would consider the trunk test a failure.

               3. Approximately 5 seconds after receiving the 60-ipm tone,
               the E9-1-1 tandem office disconnects and idles the trunk under
               test. It is not necessary for the PSAP to do any timing for a
               maintenance call, but merely react to the seizure and dis-
               connect from the E9-1-1 tandem office.


     4.1 Change to Query Protocol

     The change to the ANI delivery protocol will necessitate a corresponding
     change in the ALI database query protocol. In short, the NPD digit will
     be replaced by the three digit NPA. No other modifications are en-
     visioned at this time.

     The resulting protocol will be as follows:




     No modifications are required for ACK’s, NAK’s, heartbeats or ALI text
     messages sent from the ALI/DMS to the PSAP.


     5.1 Technical References

     Document Number | Description |Issue Date

     TR-TSY-000350 Bellcore. E9-1-1 Public Safety Answering Point: Issue 1,

     Interface Between a 1/1AESS Switch and

     Customer Premise Equipment

     NENA-04-001 NENA. Generic Standards for E9-1-1 PSAP Issue 1, 1996

     N/A E9-1-1 ALI Multiplexer System 1988

     (ALI/DMS) PSAP -Node Interface

     Specification (AT&T)

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