Panasonic KX-TD816 User Manual page 238

6.5 Specifications
Characteristics
Item
Maximum Number of Station
Instruments per Line
Ring Voltage
Environmental Requirements
238
1 or 2 by Parallel or eXtra Device Port Connection
70 Vrms at 25 Hz depending on the ringing load
0 - 40 °C, 10 - 90% relative humidity
Description
Appendix