4. Technical Parameters

Telephone Parameters

Parameter	Value	Conditions
Minimum required off-hook line current	15 mA	Off-hook
Minimum required on-hook line voltage	20 V	Hang-up
DC voltage drop (off-hook)	< 8 V < 16 V	I = 25 mA I = 50 mA
Lead current while hang-up	< 25 μA	U = 60 V
Off-hook AC impedance	220 Ω + 820 Ω 115 nF parallel	20 to 60 mA
Return loss	> 10 dB	20 to 60 mA
Bandwidth	300 to 3500 Hz	20 to 60 mA
Ringing impedance	> 2 kΩC = 1 μF	25 to 50 Hz
Ringing detector sensitivity	10 to 20 V	25 to 50 Hz
Time of response to ringing	Variable
Pulse dialling	40/60 ms	20 to 60 mA
DTMF level	−6 and −8 dB ±2 dB	20 to 60 mA
DTMF detector sensitivity	Min. −40 dB	20 to 60 mA
Dial tone detector sensitivity	Min. −40 dB	350 to 500 Hz
Busy tone detection speed	Variable	350 to 500 Hz
Continuous tone detection speed	Variable	350 to 500 Hz
Ringing tone detection speed	Variable	350 to 500 Hz
Overvoltage protection – common mode	1000 V	8/20 μs
Overvoltage protection – between A, B conductors	1000 V	8/20 μs

Other Parameters