Number Assignment Module.
A part of the phone that stores a wireless device's phone number, lock code, timer reset code and other user information. The NAM is programmed by the service provider when a device is activated. The NAM also associates the Mobile Identification Number (MIN) with the Electronic Serial Number (ESN).
Some wireless phones have dual or multi-NAM features which allows the user to have more than one phone number. (Two "lines" on one phone.)
Check out a fun infographic that teaches you how to increase storage, enhance security, improve battery life and clean your device.