Why not both? UID and number?

Mosen is right, I too have a number of contacts with two or more mobile numbers each, plus home, work etc. Knowing which number called me is often an existential question.

While on the topic, how do people organise business contacts? Sailfish's address book is not really designed very well for cases where you have only the company name and the phone number but no person. And even if I have the person's name, "Red Kite Roofing calling" or "Joe Blogs from Red Kite Roofing calling" is much better than just "Joe Bloggs calling".