Communication system

An IP phone for audio communication over a network, comprising:

• a connection controller to control a connection interface with a mobile phone and to obtain a phone number of the mobile phone being connected to the IP phone;
• a connect information transmitter to transmit connect information including identification information and the phone number when the mobile phone is connected to the IP phone;
• and
• an audio interface controller, when sending a request to an audio control server to call a receiver's mobile phone and receiving a connection unable notification indicating that the receiver's mobile phone is not connected to another IP phone, to cancel the request to the audio control server and to request the mobile phone being connected to the IP phone to call the receiver's mobile phone through a mobile phone network which bypasses the IP phone, so as to establish communication between the mobile phone and the receiver's mobile phone, wherein the IP phone communicates with the receiver's mobile phone through the mobile phone and the mobile phone network.

A telephone communication method for audio communication with telephones over a network, comprising:

• controlling a connection interface with a receiver's mobile phone and obtaining a phone number of the receiver's mobile phone being connected to a second IP phone;
• transmitting connect information including identification information and the phone number when the receiver's mobile phone is connected to the second IP phone;
• storing and managing the connect information received;
• transmitting a connection unable notification to a first IP phone once it is determined based on the connect information that the receiver's mobile phone is not connected to the second IP phone when the first IP phone sends a request to an audio control server to call the receiver's mobile phone;
• and
• cancelling the request sent from the first IP phone to the audio control server, and establishing communication between a caller's mobile phone being connected to the first IP phone and the receiver's mobile phone by requesting the caller's mobile phone to call the receiver's mobile phone through a mobile phone network which bypasses the first IP phone, when the connection unable notification is transmitted,
• wherein the first IP phone communicates with the receiver's mobile phone through the caller's mobile phone and the mobile phone network.