To call back is to telephone somebody again who called you first. I will call back later, ask him to call back, call back after five.
It carries an obligation, since to call back answers a call already made. The noun made from it also means a second audition, which is a separate use.
1phrasecall backTo phone someone again who called you first.
“Leave a number and somebody will call back within the hour.”
call back is a phrase.
Also accepted in games: ring back, phone back
callback Deverbal from call back.
Etymology from Wiktionary, CC BY-SA
Practised in Phrasal Verbs