TouchLine Key Signaling

Signaling protocol

The analog station interface uses two types of signaling protocols, Current Signaling and Tone Signaling

Current Signaling

The a/b-wires are the loudspeaker wires, and the c/d-wires are the microphone and digit selection wires. Approximate current values are (the currents in a/b-wires for display station is shown in brackets):

a/b-loop:

On-hook: 3mA (13 mA)
Off-hook: 0 mA (10 mA)
M-Key: 10 mA (20 mA)
C-key: 20-25 mA (30-35 mA)

c/d-loop:

ID (key press): 10 mA
Open: < 1 mA
Private: 3 mA

Digit Signaling

Station keyboard digits 0 - 9 use sinewave tones in the range 500Hz to 2300 Hz, at 200 Hz steps.

Digit 0: 500 Hz
Digit 1: 700 Hz
Digit 2: 900 Hz
Digit 3: 1100 Hz
Digit 4: 1300 Hz
Digit 5: 1500 Hz
Digit 6: 1700 Hz
Digit 7: 1900 Hz
Digit 8: 2100 Hz
Digit 9: 2300 Hz

Extended Digit Signaling

In addition to the keyboard digits 0 - 9 another set of 10 tones are used for DAK signaling for CRM IV, Dual Display and PrisCom stations.

These tones 10-19 are sinewave tones in the range 600Hz to 2400 Hz, at 200 Hz steps.

DAK Signaling

DAK (Direct Access Key) is the speed-dial buttons on the station.

Master station DAK keys use a combination of current signaling (M) and digits:

DAK 1: M + digit 0
DAK 2: M + digit 1
DAK 3: M + digit 2
DAK 4: M + digit 3
DAK 5: M + digit 4
DAK 6: M + digit 5
DAK 7: M + digit 6
DAK 8: M + digit 7
DAK 9: M + digit 8
DAK 10: M + digit 9

When "Hot-Line" function is enabled, Off-Hook is mapped to DAK 7 and On-Hook to DAK 8.

CRM IV and Dual Display Stations also use a combination of current signaling and digits:

D1-D10: M+0 - M+9
D11-D20: digit 10-19
D21-D30: M+10 - M+19
D31-D40: C+0 - C+9
D41-D50: C+10 - C+19
D51-D60: (Prefix +) M+0 - M+9
D61-D70: (Prefix +) digit 10-19
D71-D80: (Prefix +) M+10 - M+19
D81-D90: (Prefix +) C+0 - C+9
D91-D100: (Prefix +) C+10 - C+19

Prefix = ID+C

Priscom Stations use so called Two Tone DAK Signaling which is a combination of Extended Digit Signaling and Digit Signaling:

Key board digit 0-9: Digit Tone 0-9

DAK D1-D15: Digit tone 10 + 0 to 10 + 14

DAK D16-D30: Digit tone 11 + 0 to 11 + 14

DAK D31-D45: Digit tone 12 + 0 to 12 + 14

DAK D46-D60: Digit tone 13 + 0 to 13 + 14

DAK D61-D75: Digit tone 14 + 0 to 14 + 14

DAK D76-D90: Digit tone 15 + 0 to 15 + 14

DAK D91-D100: Digit tone 16 + 0 to 16 + 9

Substations use current signaling only:

DAK 1: ID
DAK 2: ID + M
DAK 3 ID + LT (off-hook)

Optional DAK Acknowledge

A station using Two Tone DAK Signaling can be configured with acknowledge on DAK keys:

The AMC application will send an acknowledge message by the Display Text Protocol.
The station will acknowled this by sending tone 18.