Added main line apparatus
Apparatus for selectively alerting party line subscribers
Frequency responsive party telephone line selection apparatus an
Frequency responsive selective ringing circuit
Frequency ring director
Method and apparatus for providing extension management in...
Personal telephone adapter
Polarity ring director
Polarity ring director
Programmable selective ringing circuit and method for party tele
Selective ringing circuit for a telephone
Telecommunications device with means for learning and responding
Telephone answering system and apparatus for direct caller selec
Telephone answering system and apparatus for direct caller selec