Article ID: 1605 Q&A   TR-08 T1 Signalling Bits Q: TR-08 T1 Signalling 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 Single Line Party (Loop Start) System Status TXA TXB RXA RXB Comments On-hook/IDLE 0 0 1 1 Idle mode on T1 and 2W Off-hook on 2W 1 0 1 1 2W side is off-hook Call Complete 1 0 1 1 Both 2W side and T1 is off-hook Incoming ringing 0 0 1 1/0 T1 tells us to output ringing voltage Far End Disconnect -- -- 1 0 Far end has went back on-hook; should pull battery, but 750 FXS and TSU FXS do NOT! Reverse Battery -- -- 1/0 1/0 Telco tells us to reverse battery; only valid when Answer Supervision enabled Unequipped 1 1 -- -- No card installed; not mapped Channel Test -- -- 0 1 Telco has channel in a test mode Universal Voice Grade (UVG - Loop Start) System Status TXA TXB RXA RXB Comments On-hook 0 0 0 1/0 2W and T1 are on-hook Off-hook on 2W 1 0 0 1/0 2W side is off-hook Call Complete 1 0 0 1/0 Both 2W side and T1 is off-hook Incoming ringing 0 0 1 1/0 T1 tells us to output ringing voltage Far End Disconnect -- -- 0 0 Far end has went back on-hook; pull battery from 2W Reverse Battery -- -- 1/0 1/0 Telco tells us to reverse battery; only valid when Answer Supervision enabled Unequipped 1 1 -- -- No card installed; not mapped Channel Test -- -- 0 1 Telco has channel in a test mode Universal Voice Grade (UVG - Ground Start) System Status TXA TXB RXA RXB Comments On-hook 0 0 0 0 2W and T1 are on-hook; 2W TIP OPEN Ring ground 0 1 0 0 2W side detects ring ground Tip ground return 0 1 0 1/0 Tip ground return detected from T1 side Off-hook/Loop closure 1 0 0 1/0 2W side detects loop closure Call Complete 1 0 0 1/0 Connection established Incoming ringing -- -- 1 1/0 T1 tells us to output ringing voltage Far End Disconnect -- -- 0 0 Far end has went back on-hook; pull battery from 2W (TIP OPEN) Reverse Battery -- -- 1/0 1/0 Telco tells us to reverse battery; only valid when Answer Supervision enabled Unequipped 1 1 -- -- No card installed; not mapped Channel Test -- -- 0 1 Telco has channel in a test mode If you experience any problems using your ADTRAN product, please contact ADTRAN Technical Support.

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 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) System Status RXA RXB TXA TXB Comments 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) System Status RXA RXB TXA TXB Comments 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) System Status RXA RXB TXA TXB Comments 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) System Status RXA RXB TXA TXB Battery Comments 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) System Status RXA RXB TXA TXB Battery Comments 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) System Status RXA RXB TXA TXB Tip Ground Ring Ground Comments 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) System Status RXA RXB TXA TXB Tip Ground Ring Ground Comments 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) System Status RXA RXB TXA TXB Comments 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) System Status RXA RXB TXA TXB Comments 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) System Status RXA RXB TXA TXB Comments 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) System Status RXA RXB TXA TXB Comments 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) System Status RXA RXB TXA TXB Comments 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) System Status RXA RXB TXA TXB Comments 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) System Status RXA RXB TXA TXB Comments 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 System Status RXA RXB TXA TXB Comments 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.