I'll call you back as soon as I can.
'Richiamo' — ri-KYA-mo. Stress on the second syllable. 'Appena' — ap-PE-na, stress on the second.
Use when you need to end a conversation quickly to deal with something urgent, promising to call back with a full explanation or to reschedule.
'Richiamare' (to call back) uses the prefix 'ri-' (re/again). 'Appena posso' (as soon as I can) is a standard Italian phrase signalling prompt follow-up. This phrase is typically used on the phone rather than via message.
Ci sentiamo dopo.
We'll talk later.
'Sentirsi' (to hear each other) — the standard Italian phrase for 'we'll be in touch'
Ti mando un messaggio più tardi.
I'll send you a message later.
More specific — implies WhatsApp or SMS rather than a call
Ti faccio sapere.
I'll let you know.
Common closing phrase — commits to communicating without specifying how
Italians expect promised callbacks to happen promptly. 'Dieci minuti' (ten minutes) is often optimistic but signals genuine intention. Not calling back when promised is a social slight that gets remembered.