If you have several phones for a single contact that can't be titled using the drop down menu you can add a comment after the phone number if you precede it with a # sign. eg. (123) 555-1234 # alternate work phone.
This way you can tell which number you want to call without having to add more contact files which makes it difficult to find the number you want to call.
If you leave out the # sign the phone will translate the comment into numbers and try to dial them - - or tell you that the number is not valid.