Network-based intercom system and method for simulating a...
Office line selecting technique of a telephone switching system
On-hold messaging system and method
On-hold messaging system and method
On-hold messaging system and method
On-hold messaging system and method
On-hook customer premise equipment alerting signal detection
Outside-LAN connectable IP key telephone system, terminal...
Page-mapped multi-line telephone communication system
Play and plug telephone system
Premises page/intercom system utilizing telephone set component
Private branch exchange and private branch exchange control...
Private branch exchange and telephone switching system
Private branch exchange capable of discriminating different type
Private telephone system with unified command feature
Process, arrangement, devices for seizure of a shared...
Providing multiple line functionality using alternative...
Pushbutton telephone system
Radio communication system having a base unit control for establ
Resetting circuit in a key-telephone system