What is TransUnion's Phone Number? Phone numbers for credit reporting agencies (CRA's), such as Experian, Equifax, and TransUnion, are often hard to come by. Sometimes the best thing to do is to get through to someone, anyone, explain your situation, and ask them to direct you to the right department. Here are some phone numbers to try to reach TransUnion: TransUnion's Phone Numbers: Disputes: 800-916-8800. Fax: 610-546-4605 or 610-546-4758. Please also keep in mind that CRA's often change their phone numbers. An actual credit report from the agency you are trying to reach is the best resource, as dispute telephone numbers are often listed on the report.