I agree with Luis, but it does depend on how your data may expand in the future. We have a CRM application where there are several 'standard' phone numbers for contacts (fax, mobile, home, work direct, work switchboard, etc.) but we have to allow additional number types such as 'Secretary', '2nd home', 'mum' (I kid you not, that is an actual example) which are defined by the user on entry.