iPhone Contact List - Custom Labels recognized as a Mobile Number

When a number is labeled as "mobile" in your contact list, you can click the little "cloud" shortcut to send a text message to that number.

If the number is labeled as "Home" or anything else, that text message short cut goes away (because the system thinks it is not a mobile number)

My question is, can you use a custom label and somehow tell the system that the number is a mobile number so you can send text messages to it?

I have a lot of contacts that have more than 1 cell phone and it would be nice to be able to label them as something other than "mobile" so that I know which cell phone i'm texting.

Having all the numbers labeled "mobile" does nothing to let me know which number is which.