Calls are really, really bad for shared knowledge building. Either you require each call to end with a note, discourage one-to-one calls and favor group calls, or accept that the speed of knowledge diffusion in the team will slow down to a crawl. I believe it's easy to see the downsides of all of these possibilities.
Mailing lists, Usenet, IRC, Slack, bulletin board, wiki, GitHub issues - doesn't matter which, use whatever works for you and is most convenient, but, whatever you do, please communicate in text. Bonus points for storing all that text in a searchable place.
Well, once the speech to text is sufficiently accurate, this may change (although there's always that chilling feeling of having so many of your voice samples sent to Google) - but until then, communicate in text as much as possible. Both deaf people, social phobiacs, and new hires will thank you for that.