Numeric id gets entered as phone number?

My wife retired and is now substituting in our local school system. She wants to take the automated sub calls on her iPhone 4S, but when the auto caller asks for her numeric ID and she enters it, the phone throw in a dash -, as if she were entering a phone number. She's not able to go any further with the job assignment. Any ideas on how to override this auto insert? 😕 Thanks. Larry