contact numbers appear without parentheses for area code and hyphenation. Region format set up as United States. iPhone 4S and iOS5.0

[....years later...] I had this problem arise unexpectedly (i.e. after the formatting had been there) on an iPhone7 set to U.S. region and language. What fixed it for me was changing my region and format to another country (U.K.) and then changing it back. Go to Settings>General>Language & Region then select (temporary) new region. Tap "Done" and accept change (will ask about language setting, which I chose to switch too, UK English). The phone goes black with letters setting region, then returns. The phone number format was corrected in Contacts at this step. I then changed region and language back, and all was good. So, I'm not sure a "Restore" is needed to fix this issue. It certainly is not one covered in many (any) support discussions that I could find.

I'm having the same exact problem. Is there a solution to this yet? Mine is a new Verizon account. I installed from a backup of an iPhone 3G that ran on AT&T. My wife installed the same way and is not experiencing this problem.

The solution for me was to backup my phone to iTunes, then do a Restore. Do the restore from the backup do not install as a new phone. All of my contacts had the proper format after the restore.