Place it in the middle of a waiting scene, after the call connects and before the agent finally answers, then break the wait with a bell ding when someone picks up or a classic error sound when the call drops.
Über diesen Sound
This 24-second clip plays Opus No. 1, the gentle piano melody widely recognised as telephone hold music, with soft, unhurried notes and a calm, looping feel. It gives a patient, slightly nostalgic feeling, like waiting politely while something happens elsewhere, and it works because listeners recognise it instantly as the sound of being put on hold.