Here's the answer to your question: What is an MIS #?
An MIS number is the provider identification number assigned to you by Magellan. This number allows Magellan to process your claim efficiently and makes sure the claim is paid to the appropriate provider and at the appropriate rates. Your MIS number may be printed on your authorization letters or on a Magellan EOP statement. If you are unable to locate your MIS number, you may call the Provider Service line at (800) 788-4005 to request it.