Function: noun
Date: 1986
: a telephone service that signals (as by a beep) to the user when an incoming call is received during a call in progress
Function: noun
Date: 1986
: a telephone service that signals (as by a beep) to the user when an incoming call is received during a call in progress
Merriam Webster Collegiate English Dictionary. Merriam Webster - Энциклопедический словарь английского языка. 2012