Iowa is poised to make some telephone history this weekend.Iowa Utilities Board spokesman Rob Hillesland says Sunday is the start of a five month transition period to the new 6-4-1 area code that’s being carved out of the old 5-1-5 area. Callers can use both area codes until December 3rd when the 6-4-1 code becomes mandatory. Hillesland says the transition period is a time for businesses and private customers to notify friends and clients of the change. It’s also a time for reprogramming and testing of phone equipment. Businesses can dial 641-421-0021 to test their equipment using the new area code. Hillesland says people in the new area code should also have their cell phones re-programmed. This is the first new area code for Iowa since the system was started in 1947.