Update your PRL version

CDMA phones (such as those on the Sprint or Verizon) utilize an on-device listing of cellular towers--called the Preferred Roaming List (or PRL)-- to assist your phone in connecting to the best available tower on both your home carrier or those you are able to roam on. You cellular carrier will update this listing on their servers, but your phone does not automatically get this update. In order to determine what version of the PRL your device has, open up the Device Info app (), scroll down to the bottom of the page and tap the "More Info" button, and then look on that bottom of the next page for the current PRL number.

Different carriers have different methods to update your PRL.  For example, to determine if there is an update to the PRL for Sprint, open the Phone App, swipe down from the top-left corner to bring down the Phone application dropdown menu and select "Preferences". Once the Phone Preference screen appears, scroll down to the bottom and tap "Update PRL". The phone will check to see if a new PRL is available and install the update if available.

To update your PRL on Verizon, open the phone app and dial *228 and select option 2 (thanks for the comments below for this information)