This is the final week you can dial 3-1-9 and still get your call through to the new 5-6-3 area code. The new 5-6-3 area code on the eastern edge of the state was split away from the 3-1-9 area. For the last nine months callers have been able to use either three-digit code and get through. That all changes Sunday.Iowa Utilities Board spokesman Rob Hillesland says you’ll get an error message after Sunday if you don’t dial the right number. Hillesland says the nine-month transition period has helped the process go smoothly.When the 5-1-5 area code was split up, there was only a five-month transition period, and there were more problems. Hillesland says businesses should keep letting people know about the change.Hillesland says Iowa should be able to go another eight to ten years without needing to create another area code.