We’ve discussed this in a few places, but I want to make it a formal policy.
ACME is a 100% remote company, and we’re totally in on that. Our business is built on remote teamwork! However, we do want to ensure that everyone gets some deeper human interaction with their teammates each week. Thus, it is company policy that every employee (and interns) should have at least one 30 minute voice and/or video call with at least one teammate per week. 
More than that is not strictly necessary, but we do think that’s the realistic minimum for remote teamwork. For most of you, this requirement should normally be satisfied by your weekly-call, which should be capped at one hour maximum.
If for whatever reason you don’t have your weekly team call, or otherwise can’t make the call, please try to make up that time if you can – we don’t want people to go a full working week without any voice and/or video team interaction, if it can be avoided.
It doesn’t have to be super structured, any kind of call is fine – ad-hoc pairing on a specific problem, a brief catch-up call with a teammate working on something totally different than what you’re doing .. whatever you think makes sense. We trust your judgment.
Full time employees / contractors: I have a once weekly call with someone else in the company.
Part time employees / contractors: I have a call with someone else in the company every 6 weeks.