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T1 Voice Signaling Bits

T1 Voice Signaling Bits

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)

System Status

RXA

RXB

TXA

TXB

Comments

1

Idle0101Loop open; No ringing

2

Ringing00/101Ringing cadence follows RXB

3

FXS senses off-hook0111Ringing tripped, phone is off-hook

4

Connection complet0111Talking

5A

FXS senses on-hook0101Disconnection, phone is on-hook

5B

Far end disconnect1111Far end phone hangs up. 500 ms battery removal while receiving 11.

6B

Idle0101Disconnection, phone is on-hook, Idle
FXS LOOP-START MODE

(Originating a call from a FXS 2W interface)

System Status

RXA

RXB

TXA

TXB

Comments

1

Idle

0101

Loop open; No ringing

2

FXS goes off-hook

0111

Off-hook, drawing dialtone

3

Dial address digits

0111

Dial-pulsing or passing DTMF

4

Addressing complete

0111

Dialing done, answered and talking

5A

FXS senses on-hook

0101

Disconnection, phone is on-hook (loop open)

5B

Far end disconnect

1111

Far end phone hangs up. 500ms battery removal while receiving 11.

6B

Idle

0101

Disconnection, phone is on-hook, Idle

FXO LOOP START MODE

(Receiving call into FXO 2W interfac)

System Status

RXA

RXB

TXA

TXB

Comments

1

Idle

0101

Loop open; No ringing

2

Ringing

0100/1

TXB follows ringing cadence

3

FXO goes off-hook

1100

Ringing tripped, FXO is off-hook

4

Connection complete

1101

Talking

5A

Far end disconnect

0101

Far end phone hangs up.

6A

FXO goes on-hook

0101

Disconnection, phone on-hook, idle

5B

FXO goes on-hook

1111

Send "far end disconnect" signal

6B

On-hook

0101

Idle

FXO LOOP START MODE

(Originating call out of 2W interface)

System Status

RXA

RXB

TXA

TXB

Comments

1

Idle

0101

Loop open; No ringing

2

FXO goes off-hook

1101

Off-hook, drawing dialtone

3

Dial address digits

1101

Dial-pulsing or passing DTMF

4

Addressing complete

1101

Dialing done, answered and talking, connected

5A

Far end disconnect

0101

Far end phone hangs up.

6A

FXO goes on-hook

0101

Disconnection, phone on-hook, idle

5B

FXO goes on-hook

1111

Send "far end disconnect" signal

6B

On-hook

0101

Idle

FXS TANDEM LOOP START MODE

(Receiving a call into FXS 2W interface, wink start and loop-reverse battery enabled)

System Status

RXA

RXB

TXA

TXB

Battery

Comments

1

Idle

0000Normal

On-hook

2

Incoming call

1100Reversed

On-hook, Battery Polarity Reversed

3

Wink back to network

1111Reversed

Wink to Network (250 ms)

4

Wink done

1100R

Wink is finished

5

Ringing FXS port

1100R

Ringing 2S on 4S off, rings when 0

6

Off hook (near end) Connection established

1111R

Ringing stops, talk path is open

7

On-hook

1100R

Near end hangs up

8A

Disconnect (far end)

0000R

Far end hangs up

9A

Disconnect (far end)

0000Off

Battery off (600 ms)

10A

Idle

0000Normal

Battery normal polarity

7B

Disconnect (far end)

0011R

Far end hangs up

8B

Disconnect (far end)

0000Off

Battery off (600 ms) signaling disconnect to analog equipment

9B

Near end hangs up

0000N

Battery normal polarity

10B

Idle

0000N

On-hook

FXS TANDEM LOOP START MODE

(Originating a call from FXS 2W interface, wink start and loop-reverse battery enabled)

System Status

RXA

RXB

TXA

TXB

Battery

Comments

1

Idle

0000Normal

on-hook

2

Off-hook

0011N

loop closed

3

Off-hook, start wink

1111Reversed

wink back from network (140-290ms)

4

Off-hook finish wink

0011N

dial-tone

5

Dial pulsing

0011N

send address info DTMF or dial pulse

6

Off hook addressing done

0011N

far end ringback

7

Off-hook, far end answer, Connection established

1111R

far end answers, talk path is open

8A

On-hook

1100R

near end hangs up

9A

Disconnect (far end)

0000R

far end hangs up

10A

Disconnect (far end)

0000Off

Battery off (600 ms)

11A

Idle

0000N

On-hook

8B

Disconnect (far end)

0011R

Far end hangs up

9B

Disconnect (far end)

0000Off

Battery off (600 ms) signaling disconnect to analog equipment

10B

Near end hangs up

0000N

11B

Idle

0000N

On-hook

FXS GROUND-START MODE

(Receiving a call into FXS 2W interface)

System Status

RXA

RXB

TXA

TXB

Tip Ground

Ring Ground

Comments

1

Idle

1101UngroundedU

On-hook

2

Tip gnd asserted

0101GroundedU

Line seized

3

Tip gnd & ringing

0001GU

RXB follows ringing cadence

4

Tip gnd & not ringing

0101GU

Line seized, no ringing

5

Off hook (loop closed)

0111GG

Loop closed, connection established

6A

Far end (FXO) disconnect

1111UG

Call disconnecting

7A

Idle

1101UU

Loop open returned to far end

6B

Near end (FXS) disconnect

0101GU

Loop open from far end

7B

Idle

1101UU

Idle

FXS GROUND-START MODE

(Originating a call from FXS 2W interface)

System Status

RXA

RXB

TXA

TXB

Tip Ground

Ring Ground

Comments

1

Idle

1101UngroundU

Idle condition

2

Ring gnd detected

1100UG

3

Tip gnd returned

0100GroundG

Tip-gnd returned in response to ring-gnd

4

Loop closed

0111GG

Send loop closure out NI(T1)

5

Dial pulsing

010/11GG

Passing address digits or DTMF

6

Connection established

0111GG

7A

Far end disconnect

1111GG

No Tip-gnd, call disconnecting

8A

Idle

1101UU

8B

Near end disconnect

0101GU

No ring-gnd & loop open

7B

Idle

1101UU

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)

System Status

RXA

RXB

TXA

TXB

Comments

1

Idle

0X00

Tip open at FXS output

2

Tip ground

1X00

Incoming call

3

Wink back to network

1X11

Wink back for 250ms

4

Wink done

1X00

5

Ringing FXS port

1X00

Ringing 2s on 4s off

6

Ring ground or ring tip

1X11

Off-hook, loop closed

Connection established

1X11

7A

On-hook (near end)

1X00

Near end hangs up

8A

Disconnect (far end)

0X00

Tip not grounded

9A

Idle

0X00

Idle, tip open at 2W interface

7B

Disconnect (far end)

0X11

Far end hangs up

8B

Idle

0X00

Tip open at 2W interface

FXS TANDEM GROUND START MODE

(Originating a call from FXS 2W interface, wink start)

System Status

RXA

RXB

TXA

TXB

Comments

1

Idle

0X00

Tip open at 2W output

2

Ring ground, GS seized

0X11

2W seized

3

Start wink

1X11

Tip grounded, Wink back from network (140-290 ms)

4

Finish wink

0X11

Loop closed/off-hook, dial tone

5

Dial pulsing

0X0/10/1

Send address info DTMF or dial pulse

6

Off hook (near end)

0X11

Addressing finished, far end ringing

7

Off hook (far end)

1X11

Far end answers

Connection established

8A

On-hook (near end)

1X00

Near end hangs up

9A

Disconnect (far end)

0X00

Tip open at 2W interface

10A

Idle

0X00

Tip open at 2W interface

8B

Disconnect (far end)

0X11

Far end hangs up

9B

Idle

0X00

Tip open at 2W interface

FXO GROUND START MODE

(Receiving a call into FXO 2W interface)

System Status

RXA

RXB

TXA

TXB

Comments

1

Idle

0111

Idle condition

2

Tip gnd detected

0101

TXA indicates tip gnd, line seized

3

Tip gnd & ringing

0100

TXB follows ringing cadence

4

Tip gnd & not ringing

0101

Line seizure, no ringing

5

Off hook (lopp closed)

1101

Loop closed, connection established

6A

Near end (FXO) disconnect

1111

No tip-gnd, call disconnecting

6B

Idle

0111

No ring-gnd & loop open returned from far end

7A

Far end (FXS) disconnect

0101

No ring-gnd & loop open from far end

7B

Idle

0111

No tip-gnd returned from FXO

FXO GROUND START MODE

(Originating call from FXO 2W interface)

System Status

RXA

RXB

TXA

TXB

Comments

1

Idle

0111

Idle condition

2

FXO applies ring-gnd

0011

Ring-gnd applied in response

3

FXO detects tip-gnd

0001

Tip-gnd returned in response

4

FXO off-hook (loop closed)

1101

Loop closure

5

Dial pulsing

0/1101

Passing address digits or DT

6

Connection established

1101

7A

Near end (FXO) disconnect

1111

No tip-gnd, call disconnecting

8A

Idle

0111

7B

Far end (FXS) disconnect

0101

No ring-gnd & loop open from far end

8B

Idle

0111

No tip-gnd returned from FXO

DIAL PULSE TERMINATE (DPT)MODE

(Receiving a call into FXO 2W interface)

System Status

RXA

RXB

TXA

TXB

Comments

1

Idle

0X00

On-hook, normal battery polarity

2

Off-hook

1X00

Incoming call

3

Start wink (battery reversal)

1X11

PBX returns wink to request digits. Battery reversal is detected.

4

End wink (battery normal)

1X00

End of wink

5

Pulsing digits

1/0X00

Passing address digits to PBX to complete call

6

Pulsing complete

1X00

PBX has routed call, ringing station phone

7

Answer, call complete

1X11

PBX returns answer supervision by reversing battery polarity

8A

Battery normal

1X00

PBX on-hook first

9A

On-hook, Idle

0X00

C. O. disconnect, back to idle

8B

On-hook

0X11

C. O. disconnects first

9B

Battery Normal, Idle

0X00

PBX on-hook, back to idle

E&M SIGNALING

(Receiving a call into E&M interface, immediate start)

System Status

RXA

RXB

TXA

TXB

Comments

1

Idle

0000

2

Trunk seized

1100

Incoming call

3

Passing digits

0/10/100

Passing DTMF or pulse dialing digits

4

Call

1111

Connection complete

5

Far end disconnect

0011

Far end hangs up

6

Near end disconnect

0000

Idle now

E&M SIGNALING

(Originating a call from E&M interface, immediate start)

System Status

RXA

RXB

TXA

TXB

Comments

1

Idle

0000

2

Trunk seized

0011

Outgoing call

3

Passing digits

000/10/1

Passing DTMF or pulse dialing digits

4

Call

1111

Connection complete

5

Far end disconnect

0011

Far end hangs up

6

Near end disconnect

0000

Idle now

FXS PLAR

System Status

RXA

RXB

TXA

TXB

Comments

1

Idle

1X11

Idle

2

Off-hook (near end)

1X00

Ringing far end, 2S on 4S off

3

Off-hook (far end)

0X00

Connection complete

4A

On-hook (far end)

1X00

No ringing

5A

On-hook (near end)

0X00

Idle

4B

On-hook (near end)

0X11

No ringing

5B

On-hook (far end)

1X11

Idle

If you experience any problems using your ADTRAN product, please contact ADTRAN Technical Support.

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Last update:
‎03-02-2012 07:01 AM
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