can someone explain call logs/ timezones

I spend most of my time between San Francisco and Chicago however my phone/ utility bill address is New York. I can’t make sense of my calls. I read online that text and data are default to PST for TMobile but I don’t think that’s the case with calls as if that’s the case my bill shows me receiving work calls at 12am EST when I know the latest I accept is Approx 10pm. Does anyone know the answer to this? I’d have assumed it defaulted to the time zone you made the call in but who knows. I’ve to submit my work expenses calls and I’ve no idea where to start.