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Chapter 19
Feature Group D Protocol
19.1 Introduction
19.2 Capability Mask
19.3 Signaling Overview
19.4 Parameters
19.4.1 Editable Parameters
19.4.2 Non-editable Parameters
19.5 Special TCP Behavior
19.5.1 Inbound Calls: Retrieving Digits
19.5.2 Outbound Calls: Digit Format
19.1 Introduction
This chapter describes the Feature Group D (FGD) signaling protocol and TCP parameters.
This chapter provides the following information:
Overview of the signaling performed by the Feature Group D protocol.
FGD TCP parameters.
Operations that are specific to the FGD TCP within the framework of Natural Call Control.
The FGD TCP implements the specifications of the Feature Group D (FGD) switched access service. This service provides interconnection to the BOC (Bell Operating Companies) network for the provision of message telecommunications service/wide area telecommunications service (MTS/WATS) and MTS/WATS-type services. FGD service, which provides access to the trunk side of suitably equipped BOC switching systems, is available for termination and originating access.
19.2 Capability Mask
With the NCC service, an application can call
nccQueryCapability
to determine the capabilities of a protocol.
nccQueryCapability
returns a
capabilitymask
.
The
capabilitymask
of this protocol is:
0x003C806
The following table shows which capabilities the
capabilitymask
indicates are supported by this protocol:
Capability
Supported?
NCC_CAP_NO_CALL_CONTROL
no
NCC_CAP_ACCEPT_CALL
yes
NCC_CAP_MEDIA_IN_SETUP
yes
NCC_CAP_HOLD_CALL
yes
NCC_CAP_HELD_IN_ANY_STATE
yes
NCC_CAP_HELD_UNSOLICITED
yes
NCC_CAP_ACTION_WHILE_HELD
no
NCC_CAP_TRANSFER
yes
NCC_CAP_SET_BILLING
no
NCC_CAP_GET_BILLING
no
NCC_CAP_CALLER_ID
no
NCC_CAP_EXTENDED_CALL_STATUS
no
NCC_CAP_OVERLAPPED_SENDING
no
NCC_CAP_OVERLAPPED_RECEIVING
no
NCC_CAP_SEND_CALL_MESSAGE
no
NCC_CAP_SEND_LINE_MESSAGE
yes
NCC_CAP_STATUS_UPDATES
yes
NCC_CAP_CAPABILITY_UPDATES
no
19.3 Signaling Overview
Feature Group D signaling is derived from wink start signaling. Like wink start, FGD uses only two of the four bits per signaling direction supported by E1 Channel Associated Signaling (CAS) framing. The signaling channels supporting the FGD line signaling protocol are referred to as A
f
and B
f
in the forward direction, and A
b
and B
b
, in the backward direction. The forward channel indicates the condition of the
outbound
switch equipment and reflects the condition of the
calling
party's line. The backward channel indicates the condition of the
called
party's line (the
inbound
equipment).
The other bits in either direction (the C and D bits) usually have fixed values. However, their value may change from network to network.
The inbound side uses multiple winks to acknowledge reception of different series of incoming digits. The line signaling for a typical call is illustrated by the following table
State
Outbound A
f
B
f
Direction
Inbound A
b
B
b
Idle
00
\xdf
00
Seizure
11
00
Seizure Acknowledge
11
\xdf
00-11-00 (wink)
Here the outbound side starts to send the address information. This is done by means of MF tones. Feature Group D can transfer more than one digit field. This is done to speed up long distance calls. Every field starts with a `KP' tone (start of pulsing) and ends with an `ST' tone (end of pulsing). After each digits field the inbound side acknowledges the reception with a signaling bit wink.
Register signaling first field: digit spill
MF tones
00
Acknowledgment of first series of digit
\xdf
00-11-00 (wink)
Register signaling second field: digit spill
MF tones
00
Once all the address information has been transferred, the inbound side must accept or reject the call (by sending the off-hook signaling code), or reject the call by playing busy.
If the call is rejected, the outbound side should switch back to signaling AB = 00 (
idle
), clearing the line.
Clear forward and idle
00
00
If the call is accepted, the inbound side answers the call by flipping both backward bits to 1.
Answer - conversation state
11
\xdf
11
Depending on which of the sides hangs up the call first, we have a
clear back
signal, or a
clear forward
signal. Idle follows.
Inbound hangs up first: Clear back
11
\xdf
00
Outbound hangs up first: Clear forward
00
00 or 11
Idle
00
\xdf
00
:
19.4 Parameters
The FGD TCP is programmed by the parameters described below to implement the specifications of the supported countries and network operators. These are stored within the parameter category ADI.FGD.
Parameters in this category fall into two groups:
Parameters that program TCP/host interaction, or that act on features not regulated or that can change from switch to switch within the same network. You can freely edit these parameters to suit your implementation.
Parameters that are signaling-specific: changing their values invalidates approvals for the board, and may cause the board to malfunction.
These parameters are described here for reference purposes only
.
19.4.1 Editable Parameters
Users can modify the following ADI.FGD parameters:
NCC Field Name
ADI Field Name
Unit
Default
Description
optionflags
optionflags
mask
0x0
Not used
sendanididwink
signalingflags
(bit 0)
If set, generate wink between ANI and DID digits.
expectanididwink
signalingflags
(bit 1)
If set, expect wink between ANI and DID digits.
expectfinalwink
signalingflags
(bit 2)
mask
0x3
Determines if there is a final wink after digit reception:
0
There will be a final wink.
1
There will not be a wink.
19.4.2 Non-editable Parameters
The following ADI.FGD parameters are country or network-specific, and cannot be modified.
Caution:
Most of the parameters that follow are signaling-specific: changing their value will invalidate any approval certificate for the used board, and may cause the board to malfunction. These parameters are described here for reference purposes only.
NCC Field Name
ADI Field Name
Unit
Default
Description
internal
internal
internal
0x28
This parameter determines which digits identify the ID field when they are received. Note that the first digit must be 1. The second digit is extracted from this parameter.
The mask is the following:
FEDC|BA98|7654|321-
1000|0000|0010|1000
qualaddron
qualaddron
ms
50
Bit signaling qualification time for on-hook to off-hook transitions.
qualaddroff
qualaddroff
ms
50
Bit signaling qualification time for off-hook to on-hook transitions during call set-up.
qualdisconnect
qualdisconnect
ms
150
Bit signaling qualification time for off-hook to on-hook transitions after address signaling is completed.
qualpermsignal
qualpermsignal
ms
60000
Maximum time for remote end to remain off hook when trunk is not in the conversation state before a permanent signal condition is detected. Valid range is 1-65535.
defaultrejecttone
defaultrejecttone
integer
2
The default tone to play if the PC does not respond to an incoming call indication (see
waitforPCtime
):
0
Ringing
1
Busy
2
Reorder (fast busy)
winktime
winktime
ms
200
For incoming calls, the duration of the generated wink. Set this to 0 for no wink. Set to
0xFFFF
for 350+440 Hz dial tone to be generated.
prewinktime
prewinktime
ms
100
Delay after incoming seizure is detected and before the start of the wink.
wait1stdigittime
wait1stdigittime
ms
7000
The maximum time to wait for the first incoming digit after the completion of the wink.
waitfordigittime
waitfordigittime
ms
8000
The maximum time to wait for each incoming digit after the first one.
winkwaittime
winkwaittime
ms
10000
The maximum time to wait for the far end to wink for an outgoing call. Set this to 0 if no wink is expected.
maxwinktime
maxwinktime
ms
4900
The maximum duration of a detected wink.
predialtime
predialtime
ms
70
Delay to start of outgoing address signaling after end of wink is detected.
mfkpsttimeon
mfkpsttimeon
ms
80
Duration of tone on for MF, KP, and ST.
mfkpsttimeoff
mfkpsttimeoff
ms
80
Duration of tone off for MF, KP, and ST.
mfkpstampl
mfkpstampl
internal
352
Amplitude of dialed tones.
releaseguardtime
releaseguardtime
ms
1000
Minimum on-hook internal between calls.
preanswertime
preanswertime
ms
100
Delay after the application has commanded to answer, and before the answered signal is sent to the network. The FGD TCP does not play a ring tone when accepting a call, but a certain delay is necessary.
noresourcemask
noresourcemask
integer
0
Mask that controls behavior when no resource is granted on inbound calls.
0
No signaling; just send error
1
Generate wink, then send error
customSTtone1
customSTtones
0x0
Use to send customized ST tones.
customSTtone2
customSTtones
0x0
Use to send customized ST tones.
customSTtone3
customSTtones
0x0
Use to send customized ST tones.
alarmsonqualtime
alarmsqualtime
(low byte)
ms
50
Determines the qualification time for trunk alarms (time to wait after the commencement of a trunk alarm before the TCP is notified).
alarmsoffqualtime
alarmsqualtime
(high byte)
ms
20
Determines the qualification time for trunk alarm end (time to wait after a trunk alarm state ended before the TCP is notified).
19.5 Special TCP Behavior
The following sections describe operations that are specific to the
Feature Group D TCPs within the framework of Natural Call Control.
19.5.1 Inbound Calls: Retrieving Digits
For FGD, after
ADIEVN_INCOMING_CALL
is received, the following fields of the
ADI_CALL_STATUS
structure contain information relevant to the call:
Field
Description
calledaddr
The called number. Also referred to as the
Direct Inward Dial
(DID) number.
callingaddr
The calling number (if available). Also referred to as the
Automatic Number Identification
(ANI) number.
originalcalledaddr
Carrier ID information (if available).
With FGD, all digits are MFs; no DTMF signaling is used. By default, a group of incoming digits begins with a KP tone, followed by digits, then an ST tone. This may be followed by a wink, then perhaps one or more other KP-digits-ST-wink sequences.
When the TCP receives inbound digits, it checks the digits in each sequence to determine what type of information it contains, as described in the following table:
If...
And...
Then the TCP assumes that...
The first digit in the sequence is a 1
The next digit is a 0
The call is a test call. All digits go in the
calledaddr
field.
The first digit in the sequence is a 1
The following digits in the sequence match the digits specified with the
internal
parameter
The sequence contains carrier ID information. Digits are placed in the
originalcalledaddr
field
The first digits in the sequence are "95"
The call is a test call. All digits go in the
calledaddr
field.
The digits in the sequence do not match any of the above scenarios
No previous digit sequences have been received
The sequence contains ANI digits. They are placed in the
callingaddr
field.
The digits in the sequence do not match any of the above scenarios
ANI information has been received
The sequence contains DID digits. They are placed in the
calledaddr
field.
The following parameters affect the way the FGD TCP accepts, processes and presents the incoming digits to the host:
Field
Description
signalingflags
Flags controlling optional TCP behavior:
·
Bit 0 (&
0x1
): If set, generate wink between ANI and DID digits.
· Bit 1 (&
0x2
):
If set, expect wink between ANI and DID digits.
· Bit 2 (&
0x4
): If zero, then there will be a final wink after digit reception. If set, there will not be a wink.
internal
This parameter determines which digits identify the ID field when they are received. Note that the first digit must be 1. The second digit is extracted from this parameter.
The mask is the following:
FEDC|BA98|7654|321-
1000|0000|0010|1000
19.5.2 Outbound Calls: Digit Format
The FGD TCP expects the digit string to be formatted as follows:
#
c
1
.
c
y
#
a
1
.
a
m
#
d
1
d
n
where:
c
1
.
c
y
Carrier ID information.
a
1
.
a
m
ANI digits (the address of the
calling
party).
d
1
d
n
DID digits (the address of the
called
party).
#
NMS separator symbol.
To be identified as carrier ID information,
c
1
must be a 1, and digits following
c
1
must indicate to the inbound side that the digit sequence is the carrier ID.
If the first digits in the first sequence are "10" or "95", the inbound side will assume the call is a test call, and will assume all following digits are DID digits.
If there is no carrier ID information, the digit string is formatted as follows:
#
a
1
.
a
m
#
d
1
d
n
If there is no carrier ID or ANI information, the digit string is formatted as follows:
#
d
1
d
n
Note that the application should make sure that digits in the first sequence do not cause the inbound side to mistake the ANI digits for carrier ID information, or to mistake the call as a test call.
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Copyright © 1999, Natural MicroSystems, Inc. All rights reserved.
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