Final answer:
The given statement is in passive voice. To change the sentence into active voice, replace 'Who' with 'Someone' and include the subject.
Step-by-step explanation:
In the active form, the sentence 'Who called me for an interview' would become 'Someone called me for an interview.'
For example, instead of asking 'Who called me for an interview', you can say 'Someone from the company called me for an interview.'
Remember to always include the subject, which in this case is 'Someone', when changing the sentence into active voice.