MDN stands for Mobile Directory Number, and it is essentially the 10-digit telephone number that is dialed to reach a CDMA or TDMA cellphone. It is like the phone number for your mobile device. When someone wants to call you, they dial your MDN, and it allows the call to be routed to your specific device.
Before changing carriers and porting your old number to the new carrier, the MDN and the mobile identification number (MIN) are often the same. The MIN is another unique identifier for your mobile device, but it is not used for dialing purposes. Instead, it is used by the carrier to identify and authenticate your device on their network.
When you switch carriers and port your number, the MDN may stay the same, but the MIN will change. This is because the carrier assigns a new MIN to your device on their network. However, the MDN remains the same so that people can still reach you using your familiar phone number.
Having a unique MDN for each mobile device allows carriers to route calls correctly and efficiently. When you make a call, the carrier uses your MDN to identify your device and connect you to the intended recipient. Similarly, when someone calls you, the carrier uses your MDN to locate your device and deliver the call to you.
In my personal experience, I have gone through the process of switching carriers and porting my number. I remember being relieved that my MDN stayed the same after the switch because it meant that I didn’t have to notify all my contacts about a new phone number. It made the transition smoother, and I could continue using my phone as usual.
To summarize, MDN is the Mobile Directory Number that is dialed to reach a CDMA or TDMA cellphone. It is like the phone number for your mobile device and is used by the carrier to route calls to your specific device. When switching carriers, the MDN may stay the same, but the mobile identification number (MIN) may change.