DRAFT DRAFT DRAFT DRAFT DRAFT
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
National Emergency Number Association (NENA)
Network Technical Committee
Printed in U.S.A.
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
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
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.
2.0 CALL PROGRESS SIGNALS
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
(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
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
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
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. DATABASE QUERY PROTOCOL
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:
Old protocol: NPD-NXX-YYYY-POS-TRNK-CHECK-CARRIAGE RETURN
New Protocol: NPA-NXX-YYYY-POS-TRNK-CHECK-CARRIAGE RETURN
No modifications are required for ACK’s, NAK’s, heartbeats or ALI text
messages sent from the ALI/DMS to the PSAP.
Section 5. TECHNICAL REFERENCES
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
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