You can keep your phone interviews to just the basics, enough to know whether or not you want to schedule a first appointment. These are free, so I'm not sure where you live that there is a cost.

I started my call with my name and that I was looking for a therapist because my last one moved away and it's hard to find a good match. Then I asked what kind of therapy they practiced (because I did not want short-term CBT type therapy), if they did long term therapy, did they make clients fill out lists of things every week (I hate that), and were they accepting new clients.

Then, because I have a hard time saying I need to think about it, I would schedule an appointment and think about it. With one, I did more research and realized she was not for me so I cancelled. I saw another that did not feel right. Spoke to another who was not accepting new clients, but who listened to me so that she could give a good referral. Spoke to one of those referrals, liked her right away, made an appt, and it all felt right.

So, maybe start off by just saying you're looking for a therapist, have a lot of anxiety and will need to keep the interview short so that you can get through it, then ask the basics and take it from there. If there's too much pressure about making a decision, say you need to think about it, or make and appt and cancel if you change your mind after some though.