 | Article ID: 1604 |
| Q&A | |
T1 Voice Signaling Bits
Q: T1 Voice Signaling Bits
A:
Introduction
Signaling bits are used to indicate the progress of a voice call on a T1 circuit (Off-hook, On-hook, Ringing, Disconnect, etc...) These apply if you are using ADTRAN FXS/FXO/E&M voice modules. This note will explain the states of the signaling bits.
Signaling Bit Charts
FXS LOOP-START MODE
(Receiving a call into FXS 2W interface)
1 | Idle | 0 | 1 | 0 | 1 | Loop open; No ringing |
2 | Ringing | 0 | 0/1 | 0 | 1 | Ringing cadence follows RXB |
3 | FXS senses off-hook | 0 | 1 | 1 | 1 | Ringing tripped, phone is off-hook |
4 | Connection complet | 0 | 1 | 1 | 1 | Talking |
5A | FXS senses on-hook | 0 | 1 | 0 | 1 | Disconnection, phone is on-hook |
5B | Far end disconnect | 1 | 1 | 1 | 1 | Far end phone hangs up. 500 ms battery removal while receiving 11. |
6B | Idle | 0 | 1 | 0 | 1 | Disconnection, phone is on-hook, Idle |
FXS LOOP-START MODE
(Originating a call from a FXS 2W interface)
1 | Idle | 0 | 1 | 0 | 1 | Loop open; No ringing |
2 | FXS goes off-hook | 0 | 1 | 1 | 1 | Off-hook, drawing dialtone |
3 | Dial address digits | 0 | 1 | 1 | 1 | Dial-pulsing or passing DTMF |
4 | Addressing complete | 0 | 1 | 1 | 1 | Dialing done, answered and talking |
5A | FXS senses on-hook | 0 | 1 | 0 | 1 | Disconnection, phone is on-hook (loop open) |
5B | Far end disconnect | 1 | 1 | 1 | 1 | Far end phone hangs up. 500ms battery removal while receiving 11. |
6B | Idle | 0 | 1 | 0 | 1 | Disconnection, phone is on-hook, Idle |
FXO LOOP START MODE
(Receiving call into FXO 2W interfac)
1 | Idle | 0 | 1 | 0 | 1 | Loop open; No ringing |
2 | Ringing | 0 | 1 | 0 | 0/1 | TXB follows ringing cadence |
3 | FXO goes off-hook | 1 | 1 | 0 | 0 | Ringing tripped, FXO is off-hook |
4 | Connection complete | 1 | 1 | 0 | 1 | Talking |
5A | Far end disconnect | 0 | 1 | 0 | 1 | Far end phone hangs up. |
6A | FXO goes on-hook | 0 | 1 | 0 | 1 | Disconnection, phone on-hook, idle |
5B | FXO goes on-hook | 1 | 1 | 1 | 1 | Send "far end disconnect" signal |
6B | On-hook | 0 | 1 | 0 | 1 | Idle |
FXO LOOP START MODE
(Originating call out of 2W interface)
1 | Idle | 0 | 1 | 0 | 1 | Loop open; No ringing |
2 | FXO goes off-hook | 1 | 1 | 0 | 1 | Off-hook, drawing dialtone |
3 | Dial address digits | 1 | 1 | 0 | 1 | Dial-pulsing or passing DTMF |
4 | Addressing complete | 1 | 1 | 0 | 1 | Dialing done, answered and talking, connected |
5A | Far end disconnect | 0 | 1 | 0 | 1 | Far end phone hangs up. |
6A | FXO goes on-hook | 0 | 1 | 0 | 1 | Disconnection, phone on-hook, idle |
5B | FXO goes on-hook | 1 | 1 | 1 | 1 | Send "far end disconnect" signal |
6B | On-hook | 0 | 1 | 0 | 1 | Idle |
FXS TANDEM LOOP START MODE
(Receiving a call into FXS 2W interface, wink start and loop-reverse battery enabled)
1 | Idle | 0 | 0 | 0 | 0 | Normal | On-hook |
2 | Incoming call | 1 | 1 | 0 | 0 | Reversed | On-hook, Battery Polarity Reversed |
3 | Wink back to network | 1 | 1 | 1 | 1 | Reversed | Wink to Network (250 ms) |
4 | Wink done | 1 | 1 | 0 | 0 | R | Wink is finished |
5 | Ringing FXS port | 1 | 1 | 0 | 0 | R | Ringing 2S on 4S off, rings when 0 |
6 | Off hook (near end) Connection established | 1 | 1 | 1 | 1 | R | Ringing stops, talk path is open |
7 | On-hook | 1 | 1 | 0 | 0 | R | Near end hangs up |
8A | Disconnect (far end) | 0 | 0 | 0 | 0 | R | Far end hangs up |
9A | Disconnect (far end) | 0 | 0 | 0 | 0 | Off | Battery off (600 ms) |
10A | Idle | 0 | 0 | 0 | 0 | Normal | Battery normal polarity |
7B | Disconnect (far end) | 0 | 0 | 1 | 1 | R | Far end hangs up |
8B | Disconnect (far end) | 0 | 0 | 0 | 0 | Off | Battery off (600 ms) signaling disconnect to analog equipment |
9B | Near end hangs up | 0 | 0 | 0 | 0 | N | Battery normal polarity |
10B | Idle | 0 | 0 | 0 | 0 | N | On-hook |
FXS TANDEM LOOP START MODE
(Originating a call from FXS 2W interface, wink start and loop-reverse battery enabled)
1 | Idle | 0 | 0 | 0 | 0 | Normal | on-hook |
2 | Off-hook | 0 | 0 | 1 | 1 | N | loop closed |
3 | Off-hook, start wink | 1 | 1 | 1 | 1 | Reversed | wink back from network (140-290ms) |
4 | Off-hook finish wink | 0 | 0 | 1 | 1 | N | dial-tone |
5 | Dial pulsing | 0 | 0 | 1 | 1 | N | send address info DTMF or dial pulse |
6 | Off hook addressing done | 0 | 0 | 1 | 1 | N | far end ringback |
7 | Off-hook, far end answer, Connection established | 1 | 1 | 1 | 1 | R | far end answers, talk path is open |
8A | On-hook | 1 | 1 | 0 | 0 | R | near end hangs up |
9A | Disconnect (far end) | 0 | 0 | 0 | 0 | R | far end hangs up |
10A | Disconnect (far end) | 0 | 0 | 0 | 0 | Off | Battery off (600 ms) |
11A | Idle | 0 | 0 | 0 | 0 | N | On-hook |
8B | Disconnect (far end) | 0 | 0 | 1 | 1 | R | Far end hangs up |
9B | Disconnect (far end) | 0 | 0 | 0 | 0 | Off | Battery off (600 ms) signaling disconnect to analog equipment |
10B | Near end hangs up | 0 | 0 | 0 | 0 | N | |
11B | Idle | 0 | 0 | 0 | 0 | N | On-hook |
FXS GROUND-START MODE
(Receiving a call into FXS 2W interface)
1 | Idle | 1 | 1 | 0 | 1 | Ungrounded | U | On-hook |
2 | Tip gnd asserted | 0 | 1 | 0 | 1 | Grounded | U | Line seized |
3 | Tip gnd & ringing | 0 | 0 | 0 | 1 | G | U | RXB follows ringing cadence |
4 | Tip gnd & not ringing | 0 | 1 | 0 | 1 | G | U | Line seized, no ringing |
5 | Off hook (loop closed) | 0 | 1 | 1 | 1 | G | G | Loop closed, connection established |
6A | Far end (FXO) disconnect | 1 | 1 | 1 | 1 | U | G | Call disconnecting |
7A | Idle | 1 | 1 | 0 | 1 | U | U | Loop open returned to far end |
6B | Near end (FXS) disconnect | 0 | 1 | 0 | 1 | G | U | Loop open from far end |
7B | Idle | 1 | 1 | 0 | 1 | U | U | Idle |
FXS GROUND-START MODE
(Originating a call from FXS 2W interface)
1 | Idle | 1 | 1 | 0 | 1 | Unground | U | Idle condition |
2 | Ring gnd detected | 1 | 1 | 0 | 0 | U | G | |
3 | Tip gnd returned | 0 | 1 | 0 | 0 | Ground | G | Tip-gnd returned in response to ring-gnd |
4 | Loop closed | 0 | 1 | 1 | 1 | G | G | Send loop closure out NI(T1) |
5 | Dial pulsing | 0 | 1 | 0/1 | 1 | G | G | Passing address digits or DTMF |
6 | Connection established | 0 | 1 | 1 | 1 | G | G | |
7A | Far end disconnect | 1 | 1 | 1 | 1 | G | G | No Tip-gnd, call disconnecting |
8A | Idle | 1 | 1 | 0 | 1 | U | U | |
8B | Near end disconnect | 0 | 1 | 0 | 1 | G | U | No ring-gnd & loop open |
7B | Idle | 1 | 1 | 0 | 1 | U | U | No tip-gnd returned from far end |
FXS TANDEM GROUND START MODE
(Receiving a call into FXS 2W interface, wink start and loop-reverse battery enabled)
1 | Idle | 0 | X | 0 | 0 | Tip open at FXS output |
2 | Tip ground | 1 | X | 0 | 0 | Incoming call |
3 | Wink back to network | 1 | X | 1 | 1 | Wink back for 250ms |
4 | Wink done | 1 | X | 0 | 0 | |
5 | Ringing FXS port | 1 | X | 0 | 0 | Ringing 2s on 4s off |
6 | Ring ground or ring tip | 1 | X | 1 | 1 | Off-hook, loop closed |
Connection established | 1 | X | 1 | 1 | ||
7A | On-hook (near end) | 1 | X | 0 | 0 | Near end hangs up |
8A | Disconnect (far end) | 0 | X | 0 | 0 | Tip not grounded |
9A | Idle | 0 | X | 0 | 0 | Idle, tip open at 2W interface |
7B | Disconnect (far end) | 0 | X | 1 | 1 | Far end hangs up |
8B | Idle | 0 | X | 0 | 0 | Tip open at 2W interface |
FXS TANDEM GROUND START MODE
(Originating a call from FXS 2W interface, wink start)
1 | Idle | 0 | X | 0 | 0 | Tip open at 2W output |
2 | Ring ground, GS seized | 0 | X | 1 | 1 | 2W seized |
3 | Start wink | 1 | X | 1 | 1 | Tip grounded, Wink back from network (140-290 ms) |
4 | Finish wink | 0 | X | 1 | 1 | Loop closed/off-hook, dial tone |
5 | Dial pulsing | 0 | X | 0/1 | 0/1 | Send address info DTMF or dial pulse |
6 | Off hook (near end) | 0 | X | 1 | 1 | Addressing finished, far end ringing |
7 | Off hook (far end) | 1 | X | 1 | 1 | Far end answers |
Connection established | ||||||
8A | On-hook (near end) | 1 | X | 0 | 0 | Near end hangs up |
9A | Disconnect (far end) | 0 | X | 0 | 0 | Tip open at 2W interface |
10A | Idle | 0 | X | 0 | 0 | Tip open at 2W interface |
8B | Disconnect (far end) | 0 | X | 1 | 1 | Far end hangs up |
9B | Idle | 0 | X | 0 | 0 | Tip open at 2W interface |
FXO GROUND START MODE
(Receiving a call into FXO 2W interface)
1 | Idle | 0 | 1 | 1 | 1 | Idle condition |
2 | Tip gnd detected | 0 | 1 | 0 | 1 | TXA indicates tip gnd, line seized |
3 | Tip gnd & ringing | 0 | 1 | 0 | 0 | TXB follows ringing cadence |
4 | Tip gnd & not ringing | 0 | 1 | 0 | 1 | Line seizure, no ringing |
5 | Off hook (lopp closed) | 1 | 1 | 0 | 1 | Loop closed, connection established |
6A | Near end (FXO) disconnect | 1 | 1 | 1 | 1 | No tip-gnd, call disconnecting |
6B | Idle | 0 | 1 | 1 | 1 | No ring-gnd & loop open returned from far end |
7A | Far end (FXS) disconnect | 0 | 1 | 0 | 1 | No ring-gnd & loop open from far end |
7B | Idle | 0 | 1 | 1 | 1 | No tip-gnd returned from FXO |
FXO GROUND START MODE
(Originating call from FXO 2W interface)
1 | Idle | 0 | 1 | 1 | 1 | Idle condition |
2 | FXO applies ring-gnd | 0 | 0 | 1 | 1 | Ring-gnd applied in response |
3 | FXO detects tip-gnd | 0 | 0 | 0 | 1 | Tip-gnd returned in response |
4 | FXO off-hook (loop closed) | 1 | 1 | 0 | 1 | Loop closure |
5 | Dial pulsing | 0/1 | 1 | 0 | 1 | Passing address digits or DT |
6 | Connection established | 1 | 1 | 0 | 1 | |
7A | Near end (FXO) disconnect | 1 | 1 | 1 | 1 | No tip-gnd, call disconnecting |
8A | Idle | 0 | 1 | 1 | 1 | |
7B | Far end (FXS) disconnect | 0 | 1 | 0 | 1 | No ring-gnd & loop open from far end |
8B | Idle | 0 | 1 | 1 | 1 | No tip-gnd returned from FXO |
DIAL PULSE TERMINATE (DPT)MODE
(Receiving a call into FXO 2W interface)
1 | Idle | 0 | X | 0 | 0 | On-hook, normal battery polarity |
2 | Off-hook | 1 | X | 0 | 0 | Incoming call |
3 | Start wink (battery reversal) | 1 | X | 1 | 1 | PBX returns wink to request digits. Battery reversal is detected. |
4 | End wink (battery normal) | 1 | X | 0 | 0 | End of wink |
5 | Pulsing digits | 1/0 | X | 0 | 0 | Passing address digits to PBX to complete call |
6 | Pulsing complete | 1 | X | 0 | 0 | PBX has routed call, ringing station phone |
7 | Answer, call complete | 1 | X | 1 | 1 | PBX returns answer supervision by reversing battery polarity |
8A | Battery normal | 1 | X | 0 | 0 | PBX on-hook first |
9A | On-hook, Idle | 0 | X | 0 | 0 | C. O. disconnect, back to idle |
8B | On-hook | 0 | X | 1 | 1 | C. O. disconnects first |
9B | Battery Normal, Idle | 0 | X | 0 | 0 | PBX on-hook, back to idle |
E&M SIGNALING
(Receiving a call into E&M interface, immediate start)
1 | Idle | 0 | 0 | 0 | 0 | |
2 | Trunk seized | 1 | 1 | 0 | 0 | Incoming call |
3 | Passing digits | 0/1 | 0/1 | 0 | 0 | Passing DTMF or pulse dialing digits |
4 | Call | 1 | 1 | 1 | 1 | Connection complete |
5 | Far end disconnect | 0 | 0 | 1 | 1 | Far end hangs up |
6 | Near end disconnect | 0 | 0 | 0 | 0 | Idle now |
E&M SIGNALING
(Originating a call from E&M interface, immediate start)
1 | Idle | 0 | 0 | 0 | 0 | |
2 | Trunk seized | 0 | 0 | 1 | 1 | Outgoing call |
3 | Passing digits | 0 | 0 | 0/1 | 0/1 | Passing DTMF or pulse dialing digits |
4 | Call | 1 | 1 | 1 | 1 | Connection complete |
5 | Far end disconnect | 0 | 0 | 1 | 1 | Far end hangs up |
6 | Near end disconnect | 0 | 0 | 0 | 0 | Idle now |
FXS PLAR
1 | Idle | 1 | X | 1 | 1 | Idle |
2 | Off-hook (near end) | 1 | X | 0 | 0 | Ringing far end, 2S on 4S off |
3 | Off-hook (far end) | 0 | X | 0 | 0 | Connection complete |
4A | On-hook (far end) | 1 | X | 0 | 0 | No ringing |
5A | On-hook (near end) | 0 | X | 0 | 0 | Idle |
4B | On-hook (near end) | 0 | X | 1 | 1 | No ringing |
5B | On-hook (far end) | 1 | X | 1 | 1 | Idle |
If you experience any problems using your ADTRAN product, please contact ADTRAN Technical Support.
