When a number that has called before rings in, the receptionist gets a private note with the name on file. It only asks “Is this [name]?” — it never reads out an address or past jobs to someone who hasn’t confirmed who they are.
The lead is linked to the same customer record, so you see every call and job for that customer in one place. The number is taken from caller ID, so a caller who gives a different callback number still lands on the right customer.