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 | 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)
| 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)
| 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)
| 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.
