Oki 1.2 - Manual (Page 23)

15 Placing Calls
• Incoming
operation from
the IP network
during a
telephone call
using the IP
network.
Identification of incoming call
An incoming call can be identified by setting a ringing time from IP
network and from a public telephone line separately.
Example
Power failure switching
If a power failure occurs, the telephone is directly connected to a PSTN
line.
CAUTION When supplying power to a telephone set during
power failure, the polarity may be reversed
depending on a line port connection mode.