Can you hear me? Are you there?
Stress 'SEN-te'. 'Ci sei' = chi SAY — 'are you there?'
Use 'Ci sei?' when a call goes suddenly silent and you're not sure if the other person is still connected. 'Si sente?' in formal context, 'ti sento' informally.
'Si sente?' = can you be heard? (formal impersonal). 'Ci sei?' = are you there? (informal, literally 'are you there?'). Both are used when a call drops or goes silent. 'Mi sentite?' (can you all hear me?) is for conference calls.
Mi senti?
Can you hear me?
Informal 'tu' version.
Sei ancora lì?
Are you still there?
When silence follows a response.
La linea è caduta.
The line dropped.
Explaining a dropped call.
The phrase 'ci sei?' is so deeply embedded in Italian phone culture that it's also used in person ('ci sei?' = 'are you paying attention?'). Dropped calls ('chiamate cadute') are common enough in Italy that Italians have developed a smooth social convention for recovering from them without awkwardness.