Patent ID: 8189569

Claim:
An apparatus for switching between an Internet Protocol (IP) network interface port and a Public Switched Telephone Network (PSTN) port, the apparatus comprising: a central processing unit (CPU) configured to control a user port switching circuit in response to receiving a switching signal; a user port configured to couple to a user device, and the user port for generating the switching signal; the IP network interface port configured to access an IP network; the PSTN port configured to access a PSTN; a Subscriber Line Interface Circuit (SLIC) for coupling the user port switching circuit to the CPU; the user port switching circuit coupled to the CPU, the user port and the PSTN port, the user port switching circuit configured for switching the user port to a one of the IP network interface port and the PSTN port, thereby enabling the user port to access either the IP network interface port or the PSTN port, wherein the user port switching circuit further comprises, a detection circuit configured for detecting a line status of the PSTN port and sending the detected line status to the central processing unit, a holding circuit configured for maintaining an analog off-hook status on the PSTN port in response to one or more control signals from the CPU, wherein the CPU configured to: send a first control signal to a first relay of the user port switching circuit, wherein the first relay switches the user port from the IP network interface port to the PSTN port if the PSTN port is idle, send a second control signal to a second switch of the user port switching circuit to couple the holding circuit to the PSTN port, and in response to coupling, the holding circuit is configured to maintain the PSTN port in an analog off-hook status, send a third control signal to the first relay of the user port switching circuit to temporarily switch the user port from the PSTN port back to the IP network interface port, send a fourth control signal to a first switch of the user port switching circuit disconnecting the connection between the user port and the SLIC to prevent user from hearing dialing voices from the CPU, and send a fifth control signal to the first relay of the user port switching circuit, wherein the first relay switches the user port from the IP network interface port to the PSTN port enabling PSTN communication.