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 unfortunate…It really can be hard to read when someone’s open to exchanging contact info of any kind sometimes. Some folks, easy as can be, others you think it may be and then you’ve tripped their brick walls without expecting it.