I guess that can be true because my phone is usually on silent, but a message would still be preferable because a missed call in my notifications doesn't tell me much of anything.

I would also put forward that a request to talk could also take the form of a request to talk, like hey are you free to talk about my part in the xyz project?

PS. I would ask the people who you call if they would prefer a text first. It could be you're calling people who are like you, but it's also possible that you're calling people like me, and they're too polite to tell you.