Telecommunication system with radio line

Claim 1

A telecommunication system comprising a wired network and a multiplicity of posts served by said network for selectively communicating with one another, each of said posts being uniquely identified by an individual call number and comprising a relay station connected to a branch of said network and a mobile subscriber station coupled with said relay station by a radio link of limited range; said subscriber station comprising a first radio transmitter and a first radio receiver tunable to any one of a plurality of communication channels available to a group of said posts, said first radio receiver being provided with first scanning means for cyclically exploring said channels in an idle state of the subscriber station to determine their free or busy condition, said subscriber station further comprising first coding means and first comparison means connected to said first radio receiver and to said first coding means for detecting an identity between a locally generated reference code and a code received on one of said channels and for causing said first radio transmitter to send out a first verification signal on the same channel upon detection of such identity, said subscriber station additionally including selector means for initiating an outgoing call by triggering said first radio transmitter to send out a locally generated identification code on a channel found idle by said first radio receiver preparatorily to the emission of a call signal to said network in response to reception of a second verification signal on the channel found idle, said relay station comprising a second radio transmitter and a second radio receiver tunable to said channels, said second radio receiver being provided with second scanning means for cyclically exploring said channels in an idle state of the relay station to determine their free or busy condition, said relay station further comprising second coding means and second comparison means connected to said second radio receiver and to said second coding means for detecting an identity between a locally generated reference code and a code received on one of said channels and for causing said second radio transmitter to send out said second verification signal upon detection of such identity, said second radio transmitter being triggerable by an incoming call signal from said network to send out a locally generated identification code on a channel found idle by said second radio receiver preparatorily to seizing the idle channel in response to reception of said first verification signal thereover for enabling an extension of the incoming call to said subscriber station.