Definition: MDN

(Mobile Directory Number) The 10-digit telephone number that is dialed to reach a CDMA or TDMA cellphone. Prior to changing carriers and porting the old number to the new carrier, the MDN and "MIN" (mobile identification number) are often the same. When porting, the subscriber relinquishes the MIN to the old carrier and gets a different MIN from the new carrier, while retaining the MDN. Therefore, a MIN in one carrier can be the same as an MDN in another.