If you get a phone call that could have been an email it's likely because they don't want a written record of what was said. Be sure to send a followup email afterwards summarizing the call so you cover your ass.
You say "it's likely" while that has never been the case for me. There are simply people that like to talk instead of writing, without any sort of deeper meaning behind it.
It has happened to me a few times, and one of them I can share.
When I was negotiating for a new job, it was all email, until I asked whether it'll always be work from home (this was during the pandemic). Instead of an email reply, I get a call and the HR tells me it should be work from home always.
Fast forward, the pandemic is "over" and people are now being called over to work. My contract is worded ambiguously enough for the company to defend this "order". I realise if the earlier conversation was an email, I would have a case for myself that I never agreed to this (not that I would go the judicial route, but still).
I wish I could post just links to mastodon posts and lemmy would preview the content. If anyone got any info about it, lemmy know
for those also interested here's an article achieving smt similar
https://shkspr.mobi/blog/2022/11/webmentions-privacy-and-ddos-oh-my/
