Send data to Arduino via SIM900 and save it in non volatile memory?

I need to be able to send info to a unit that consists of a MEGA, SD shield and SIM900 shield. It is a remote data logger and reporting system. Want I would like to do is be able to send it an SMS that specifies a cell number of an administartor - once this number is received, it will allow the newly added administrator to execute functions on the unit remotely.

The catch is that this number needs to be saved in non volatile memory, so it can withstand a reboot. Is this possible?

That sounds perfectly feasible. Save the number(s) in the EEPROM area.