How To Write A Phone Number On A Resume . Stand out from the crowd and. Write out extension with the extension number beside it or simply write ext. with the extension number beside it on the same line as the phone number you are listing. Telephone Receptionist Resume Sample LiveCareer from www.livecareer.com Second to email, a phone number is a vital piece of information to include on your resume. Fourth, list your phone number. Free on android, ios and desktop.