DVM Signaling Format (DVM Only)
The DVM Signaling Format parameter is used to match the signaling format of the digital voice port to the interfacing PBX. The following options are available:
Tie Trunk
For tieTrunk, signaling bit A defines the on-hook/off-hook conditions as shown below. Signaling bits B, C, and D are denoted by "X", a "don't care" condition.
| | Forward | Backward |
| State | A | B | C | D | A | B | C | D |
| Idle (On-Hook) | Low | X | X | X | Low | X | X | X |
| Seized (Off-Hook) | High | X | X | X | Low | X | X | X |
| Answered | High | X | X | X | High | X | X | X |
| Busy | High | X | X | X | High | X | X | X |
Use this option when the interfacing PBX follows Tie Trunk Channel Associated Signaling (CAS) protocol emulation established by the International Telecommunications Union (ITU).
DC5B
For dc5B, signaling bits A, B, C, and D define the on-hook/off-hook conditions as follows:
| | Forward | Backward |
| State | A | B | C | D | A | B | C | D |
| Idle (On-Hook) | High | High | Low | High | High | High | Low | High |
| Seized (Off-Hook) | Low | High | Low | High | High | High | Low | High |
| Answered | Low | High | Low | High | Low | High | Low | High |
| Busy | Low | High | Low | High | Low | High | Low | High |
Use this option when the interfacing PBX follows DC5B CAS protocol emulation established by the International Telecommunications Union.
R2/Q.421
For r2Q421, signaling bits A, B, C, and D define the on-hook/off-hook states as follows:
| | Forward | Backward |
| State | A | B | C | D | A | B | C | D |
| Idle | High | Low | Low | High | High | Low | Low | High |
| Seized | Low | Low | Low | High | High | Low | Low | High |
| Seize ACK | Low | Low | Low | High | High | High | Low | High |
| Answered | Low | Low | Low | High | Low | High | Low | High |
| Clear Back | Low | Low | Low | High | High | High | Low | High |
| Clear Forward | High | Low | Low | High | Low | High | Low | High |
| | | | | | | or | |
| | | | | | High | High | Low | High |
| Blocked | High | High | Low | High | High | High | Low | High |
Use this option when the interfacing PBX follows R2/Q.421 CAS protocol emulation established by the International Telecommunications Union.
Wink Start
When CAS signaling format winkStart is selected, signaling bit A defines the on-hook/off-hook conditions as follows (signaling bits B, C, and D are denoted by "x", a "don't care condition".
| | Originating | Terminating |
| | PBX to Voice Channel | Voice Channel to PBX | Voice Channel to PBX | PBX to Voice Channel |
| Wink Start Events | Local PBX (Outgoing Call) | Local Voice Channel | Remote Voice Channel | Remote PBX (Incoming Call) |
| | A | B | C | D | A | B | C | D | A | B | C | D | A | B | C | D |
| Idle state (On-hook) | 0 | x | x | x | 0 | x | x | x | 0 | x | x | x | 0 | x | x | x |
| Time slot seized by the
local PBX | 1 | x | x | x | 0 | x | x | x | 0 | x | x | x | 0 | x | x | x |
| Local wink (from local voice channel to local PBX) | 1 1 1 | x x x | x x x | x x x | 0 1 0 | x x x | x x x | x x x | 0 0 0 | x x x | x x x | x x x | 0 0 0 | x x x | x x x | x x x |
| Local PBX sends DTMF digits to local voice channel | ....................... | ....................... | ....................... | ....................... |
| Time slot seized by the
remote voice channel | 1 | x | x | x | 0 | x | x | x | 1 | x | x | x | 0 | x | x | x |
| Remote wink sent by remote PBX to remote voice channel | 1 1 1 | x x x | x x x | x x x | 0 0 0 | x x x | x x x | x x x | 1 1 1 | x x x | x x x | x x x | 0 1 0 | x x x | x x x | x x x |
| DTMF sent to remote PBX | 1 | x | x | x | 0 | x | x | x | 1 | x | x | x | 0 | x | x | x |
| Called party answers | 1 | x | x | x | 1 | x | x | x | 1 | x | x | x | 1 | x | x | x |
Wink Start Operation
In the example shown below, a local user connected to a digital PBX attempts to reach a user connected to a remote digital PBX at station 56. Each PBX trunk is attached to a T1/E1 digital voice module (referred to as a channel in subsequent discussions) housed within a Passport 4400 unit. Connection between the two voice channels may be established over the switched network.
It is assumed that the network extension number of the remote voice channel is 1234. It is further assumed that both voice channels are configured for the winkStart DVM signaling format, and that local and remote ingress/egress tables and their respective manipulation strings are properly configured.
Following is a sequence of events involved in establishing a connection between the two users:
- The local user dials 123456.
- The local PBX stores digits 123456, and seizes the time slot by switching signaling bit A from 0 to 1. (See table in Wink Start)
- After a minimum of 100 milliseconds, the local voice channel (DVM) responds with a wink signal ranging from 140 to 290 milliseconds (200 ms nominal), then returns a dial tone.
- The local PBX forwards digits 123456 to the local DVM.
- The local DVM uses digits 1234 to establish a connection with the remote voice channel, and forwards digits 123456.
- With connection between the local and remote voice channels established,
the remote voice channel goes off-hook to the remote PBX, and starts a pre configured regeneration time delay. See Delay (High Regeneration).
- Shortly after 100 milliseconds, and before the time delay expires, the remote PBX returns a wink signal to the remote voice channel. This signal is ignored by the remote voice channel. When the time delay expires, the remote voice channel regenerates digits 56 in either dial pulse or DTMF, based on the format configured for that channel. Using the regenerated digits, the PBX rings station 56. Connection is established when the user at station 56 answers.
End of Topic
