On Hook State; Off Hook State - Samsung SCX-4720F Service Manual

4.8.5 On Hook State

• DC10V ~ DC100V, DC Resistance : 5MΩ and over
• DC150V ~ DC200V, DC Resistance : 30KΩ and over
• Ring Sensitivity
- Ring detection voltage : 40Vrms ~ 150Vrms
- Ring detection frequency : 15.3Hz ~ 68Hz
- Ring detection current : 20mA ~ 100mA
• Pseudo Ring Sound
- Ring frequency : 750Hz + 1020Hz
- Ring Interrupt period : Mark/Space controlled by CPU/Modem

4.8.6 Off Hook State

• DC Resistance
- DP Dial Mode (DC 30mA) : 50 ~ 220 Ω
- DTMF Dial Mode (DC 20mA) : 50 ~ 300 Ω
- DTMF Dialing (DC 20mA) : 50 ~ 540 Ω
• Matching (Input AC Impedance) : 600 Ω±30% for 300Hz ~ 3.4KHz
• Minimum Line Current detecting Off Hook : 20mA(Handset Hook Off)
• Minimum Line Current for DP Dial transmission : 20mA ~ 120mA
Samsung Electronics
15mA(external Handset Hook Off)
Product Margin : 20mA and over
Summary of Product
Service Manual
4-25