Communications

Telephonic Communications

With Current Controlling Electromagnetic Core Device (e.g., Hall-effect Device)

No:5651052

Apparatus and method for incoming call detection and alarm circuitry for cellular telephones

No:5729589

Apparatus and method for incoming call detection and alarm circuitry for cellular telephones

No:4046969

Dial pulse repeating line circuit using miniature line transformer

No:4027235

Direct current compensation circuit with current threshold detection

No:4707673

Directional coupling transformer for bi-directional full duplex data bus

No:7027590

Dynamic allocation of overhead voltage to support simultaneous transmission of signals on a telecommunication line

No:6980643

Fallback function telecommunications device

No:4110636

Feeding bridge

No:6020732

Flux cancelling transformer line circuit

No:3781483

Line feed and isolation transformer with integral loop supervision

No:4099032

Loop current detector

No:5912513

Method and apparatus for reducing power dissipation in dc termination circuit

No:7043012

Method and apparatus for ring again feature for a telephone system

No:7447305

Method and arrangement for filtering of signals

No:6393123

Method and modem circuit for determining connection status of a phone line

No:6233462

Portable terminal device for automatically controlling transmitting voice level and calling sound level

No:4020294

Presence and direction of line current flow detector

No:5539820

Protection of active telephone line interface circuits

No:5515433

Resistance forward telephone line feed circuit

No:4024360

Station checking network for telecommunication system

No:5138658

Subscriber line interface circuit providing regulated current

No:5970139

T1 channel bank control process and apparatus

No:7181005

Telephone interface circuit

No:4431869

Telephone line feed

No:5859906

Telephone switch hook interface circuit