call waiting

noun

a telephone service feature whereby a person engaged in a telephone call is notified by a tone that a second call is being made to the same number, and is able to talk to either party while keeping the other on hold.

Compare hold button.

Examples from the web for call waiting

To me, it is equivalent to talking to somebody on the telephone whose call waiting keeps chiming in.
Chimes for call waiting shall be suppressed by terminating call in progress and answering the call waiting.
Redial button for call transfer or call waiting when supported by telephone system.
Examples include unwanted voice mail, call waiting or toll-free calls that automatically roll over to toll calls.
Use a landline telephone, and disable call waiting so your interview is not interrupted.
Vertical services are advanced calling features such as caller identification, call waiting, and call forwarding.
Services such a call forwarding call waiting require sophisticated switches to support the user's needs.
Air medical escorts should eat regular, light meals and stay hydrated while on-call waiting for flights.
Using the phone for electronic monitoring places restrictions on access to the phone and on special features such as call waiting.