Call status recognition in a broadband private automatic branch

Call tagging user information in a telephonic environment

Call waiting service in multimedia-capable network

Call waiting-caller identification notification device

Call-waiting tone detection technique

Call-waiting tone detection technique

Caller ID system

Caller ID system with retransmitted caller ID information

Caller ID telephone with signal attenuation

Calling system for short duration data transactions

Carbon microphone interface for a modem

Carrier locating system

Cash access system and method of operation

Cellular mobile radio credit card system

Cellular mobile radiotelephone-based system for rental of mobile

Cellular telephone for acquiring data encoded in bar code...

Central monitoring station with method to process call based...

Centralized management unit receiving data from management...

Certified telephonic transmissions

Change-over system for automatic answering telephony and facsimi