Hey can u clarify things a little?
Storing users codes with the PIC's built in EEPROM shouldn't be a problem.
But what i don't understand is how the user ID numbers are input? Numeric Keypad?
As for SMS i assuming u mean Short Message Service Text messages. As to how to send these would depend on the application, you could include a modem and use a "message center" you dial up and then send the text in ASCII form, these i have found (in the UK any way) to be expensive, VERY.
Another alternative might be to interface it to a computer that has an internet connection, there are no shortage of online SMS companys that will allow you just to post the information in HTTP 1.1 some for free
.
If you want paid work at student prices feal free to private message me