Anyone offer phone support?

After listening to the lastest episode of the Indie Hackers podcast with the founder of Less Annoying CRM (great name btw!!), I'm brainstorming how we could make phone support work for us.

Our customer base, farmers in the US and Canada, definitely prefer phone support over email but we've limited it to Calendly at the moment.

I'm curious about how to handle times when all agents are busy, integrating with a help desk, and any other tips/tricks to make it work?