Adding default text within link.

Issue Summary

I have set up a link called Tracking Number on an E-Commerce site (using Drupal Commerce). Since my client only uses UPS for their shipping, I set up a Link field type where all they would need to do is enter the UPS tracking number. I would like to set up this LINK field with pre-existing text or a base path such as "http://upstracking.com/tracking_number=" so that all the client has to do is enter "AAAAA22233344" in this field so that the final URL would be something like "http://upstracking.com/tracking_number=AAAAA22233344."

Is this possible? And if so, how would I go about doing this? Thanks.