Phone number or other contact info. Supposing you’re on good terms, they’re not someone you’re interested in romantically or the like (so none of the anxiety from that at least), what’s kept you from asking?
Supposing that something has on occasion, anyway.
That’s fair, which is why I had this in the OP:
I only wrote number as a shortform way of saying contact info, which is clunkier. Is there a better short way of writing, “asking someone’s [contact info]?”