T1 Voice Signaling Bits

Version 2
    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.