The mobile telephony circuitry is coupled to the antenna.

The separate channel is established in parallel with the voice circuit.

The mobile telephony circuitry is configured to communicate with a mobile telephony network using a mobile communication protocol.

This will discharge the phone circuit and clearout its RAM.

This will discharge the phone circuit and clearout its RAM.

This discharges the phone circuit and clears out its RAM.

That is, the device for changing over and restoring automatically a telephone circuit whose application is not limited can be provided.

This will discharge the phone’s circuit and clear out its RAM.

A Radio Frequency Interference Filter (10, 12) is connectable in series in the tip (T) and ring (R) branches of a telephone circuit.

The communication link to the client is shared by a telephone circuit (29) at the client end of the link.

A telephone circuit that travels over land-based circuits (as opposed to wireless).

The apparatus utilizes the existing speech circuit (13) to keep the line current (ILO) constant at the power supply.

The invention concerns an ISDN subscriber card (ISC1, ...., ISC6) comprising a HDLC controlling circuit (4) for concentrating Internet frames so as not to use a telephone circuit for every call to an Internet access provider.

The telephone circuit further includes an optical emitting element (78) which is optically coupled with the network optical receiving element.

The invention is related to a system and a method for message annunciation in a telephone circuit by using the ring back tone as vehicle and carrying voice messages / music / jingles in a telephone system.