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SIP Operation Manual
Example for 4O gateway:
4O model connecting directly to the Telephone Line of a PSTN
P1-P4 is FXO interfaces and can all be connected to a PSTN to serve as a bridge between the
PSTN and other VoIP telephones. The system also allows a call to be made from a traditional
telephone line to connect with a user behind the gateway.
Integrating the 4O with PBX
P1-P4 is FXO interfaces and can be connected with PBX extension lines (exclusively for analog
interface, not applicable for digital type).
