What if a private seller asks me to call him

I don't see why not, as long as you have their number.

Thank you. His number is listed in the car description. Instead of all numbers, he uses numbers and words. For example : “12three-46six- 78nine”. That seemed fishy to me.

If you don't want them to have your number, block it before you call. If using a landline dial *67 then the number. Your number will be blocked on their end. Hope that helps! Jim