Telephone line access arrangement

Telephone line access box enclosure

Telephone line extension

Telephone line interface architecture using ringer inputs...

Telephone line interface circuit

Telephone line interface circuit

Telephone line interface circuit

Telephone line interface circuit

Telephone line interface circuit and method

Telephone line interface circuit with voltage control

Telephone line interface circuit with voltage switching

Telephone line interface circuit without hookswitch relay

Telephone line interface with AC and DC transconductance loops

Telephone line overvoltage protection apparatus

Telephone line power utility circuit

Telephone line sourced power supply

Telephone line unit having programmable read-only memory

Telephone line-powered power supply for ancillary equipment...

Telephone loop monitoring and isolation system

Telephone loop-current regulator