noun
hold music; music on hold; hold tone
Refers to the music or tone played while a phone call is on hold. Common in business and customer service contexts.
お待たせしている間、保留音が流れます。
Hold music will play while you are waiting.
保留音が急に切れて、担当者が出た。
The hold music suddenly stopped and a representative came on the line.
着信音 is a ringtone for incoming calls, while 保留音 is the music heard when a call is placed on hold.
Compound of 保留 (hold, pending) and 音 (sound). The exact origin is uncertain, but it likely emerged with the spread of telephone hold systems.