As a freelancer, you have to face a lot of sudden phone interviews. But, just keep in mind that they're calling you because they thought that you are eligible for the job. Keep calm, and at a medium pace answer the questions. For me, it was from food to travel, humanities and advertising. So, pick out your specialization or domain beforehand. If you can't hear them clearly just ask politely, don't be scared. If you think you've told a grammatically incorrect sentence, don't focus on it, just repeat the sentence correctly and go on. Remember another thing, that the interviewers are not your bosses, they're potential clients. If you're new to this freelancing career and you feel intimidated and nervous during the interview, that's okay, just remember you're in control. Give yourself a little time. It'll smooth out. Calmness, medium pace and polite behaviour are the ways to handle phone interviews, as per as I think. Good luck. 👍