Less typing and more talking. I imagine you would have been more productive on a call. I couldn't imaging doing pair programming without being able to talk with the person I'm pairing with.
Also to be clear, when I say "phone call" I mean audio + video. So Zoom, Hangouts, Skype, etc.
I just spent the last two hours helping a dev on my team write some code in an area of the project he was unfamiliar with. We did it all over Slack, with liberal use of code snippets. I can't imagine how a phone call would have helped.