Another thing that helps with buyers who insist on a call: put a "what I need from you" checklist at the end of your scope email, three or four short questions they can answer in two lines each (goal, deadline, who approves, anything off-limits). Most people who want a call really just want reassurance that you understood them, and answers to those questions give that in writing.

If they still want to talk, offer one 15-minute slot after they reply, and send a recap email within an hour: "Here's what we agreed: X, by Y, for Z." Ask them to reply "confirmed" before any money moves. That way the call never replaces the written record.

For your 5th point, a simple rule is that anything which promises a price, date or refund gets human sign-off, while FAQs and status updates can go out as drafts you skim quickly.