US Patent 7155187 Digital cordless telephone

The present invention improves an inconvenience of the conventional system in that cordless hand sets must be registered in advance, and reduces the power consumption in the waiting state. The digital codeless telephone according to the invention uses a public telephone network. In the system of the invention, a transmitting party calls a receiving party by means of a message having a group identification code for direct communication between personal stations and information for a waiting mode change request. The system makes the receiving party prepare for receiving, by an event that the receiving party changes the waiting mode according to the message.