Sprint, AT&T, and Verizon have all posted statements that they are offering unlimited text, calls, and date for customers affected in the path of Hurricane Dorian. However, only certain areas are included.
We specifically checked AT&T, and zip codes for Horry County and Georgetown were included, however, zip codes here in Florence and around the Pee Dee were NOT.
For Verizon, coastal counties were included, Florence, Darlington and other Pee Dee counties were NOT.
Sprint does not have specific counties/zip codes listed, but did say they will waive overage fees for Florida, Georgia, SC and NC.
Of course, this may change as the storm continues, however, it would be best to check specifically with your provider to be sure you are included.
Check your provider:
AT&T
https://about.att.com/pages/disaster_relief/storm_dorian.html
Verizon
Sprint
https://newsroom.sprint.com/sprint-to-assist-customers-in-florida-georgia-and-south-carolina.htm