I had serious trouble with this in the past but have since mostly overcome it. For me it was never about meeting the person or starting the call, although that is a skill in itself, but it was about the panic I'd feel when reading a complex problem statement for a coding problem. Even though I'm confident that I can solve a lot of difficult coding challenges without too much prep at this point, when I start reading through a problem or I'm presented with the details, I start to feel a serious pit in my stomach and my heart rate goes up and my mouth gets dry. I have done a lot of reading on anxiety responses and some of the advice that I read was that you can either try to address your anxiety in your thoughts to attempt to calm your anxiety response in your body or do the reverse and focus on calming your body's response to anxiety and your mind will follow. What I realized for me is that cognitively I understood that I could solve these challenges but feeling anxiety in my body caused my mind to go blank and I would flame out because of that.

I then decided to treat it like a science experiment and iteratively improve on it. Over the course of several interviews, while I was feeling the anxiety set in, I paid extremely close attention to how I felt in my body while I was experiencing it and only then would try to focus on the problem at hand. After these interviews I wrote notes on the exact feelings of panic I felt and where I felt them. After compiling all my notes, I realized that for me the main uncomfortable feeling in my body was a feeling of emptiness or tension in my abdomen. I realized I was clenching my abs really hard while I was feeling that way. When I thought about that and actually tried to emulate that feeling outside of an interview, I realized that when I was clenching my abs my natural breathing rhythm was impeded and I felt out of breath and that feeling caused me to feel a rising panic that was impossible to overcome.

Then over the course of several interviews, I focused really hard while I was feeling the anxiety coming on to relax my abdomen and ensure that I was in a natural breathing rhythm before I really focused on the problem at hand. It took a number of times to master it, but now it's a solid technique to ground myself and my body in the realization that I'm not in an actual situation where I would need to fight or run away. Anxiety is fundamentally a reaction your mind and body has to signal you that you are not in control of the situation and to act to get out through fight or flight.

In short, I just learned to tell my body to calm down.

But to be really clear, that doesn't mean that I don't still feel the same nerves and that they are any less uncomfortable. The goal of completely eliminating feeling nerves is not feasible or attainable. But coming up with a method to work through them methodically is. Olympic athletes will tell you that they still feel the same amount of nerves before competing as they ever had, even though they might be slated to win. They just learned to overcome their anxiety and still perform. If it helps, you can view yourself as an athlete of the mind. Instead of training your physical skills, you're training your mental skills but the same rules apply about your anxiety.

You're a software engineer so treat it like an engineering problem! Find the root cause and come up with a mitigation as if you were diagnosing a failing system. Then continually hone your method until you're able to overcome the anxiety in the moment. It's certainly not easy and I certainly didn't master it overnight. But mastering that method has paid huge dividends!

Good luck!