phone calls are my worst fear. video calls not so much because you can still use visual cues. if you can, try use your hands as much as possible. it works for me sometimes. if you think your more nervous doing a video call than a phone call, maybe minimize the window so you cant see the person. another thing to keep in mind is, your pretty much talking to a computer. youre the only person in the room. "Sorry, my internet is bad" or "sorry, you keep breaking up". those lines could help you out if you stutter lol