Rule reminder
The negative cleft (Non è...che) is used to CORRECT or CONTRAST information. It denies that one element is responsible for something and often introduces the real element. Pattern: Non è + [wrong element] + che + clause, (è + [correct element]). Example: Non è Marco che ha sbagliato, è Luigi. This structure is extremely common in spoken Italian for corrections and clarifications.
Someone says 'Hai chiamato tu?' You want to say it was NOT you but your brother. Which sentence is correct?