Strange problem! I want to back up my 1650 messages

SOURCE: SIM card registration failed

You might have filled up the memory to the brim and the phone doesn't have enough to switch on.
Try reformat to original settings. anything you stored on the phone will be lost.

How to reformat your phone, first turn it OFF. Press * 3 send at the same time and keep them pressed while you turn the phone on.
Give it time to work.

Remember, do not let go the 3 keys until you see the formatting screen.
After a few minutes when the process is over, your Nokia N70 will be back to the original delivered system.

SOURCE: the phone keeps displaying sim card registration failed on phone

you have to enter some code after u enter the sim

check out this link
http://www.gsmliberty.net/shop/nokia_unlock.php

i dont assure you but i think it will help you.
thanks.

SOURCE: my nokia 5300 handset not working in all sim card

this phone might have been made only to detect the airtel sim cards as the phone in question might have been made only for the air tel company
in collaboration with nokia .

so there might be no code for it to allow all the sim cards .

imagine it like the cdma phone distributed by reliance communications

SOURCE: nokia e65 will not accept any sim card after i unlocked the phone

I would try the unlock again, it sounds like the unlock was unsuccessful otherwise it would have allowed you to use the other sim cards.

SOURCE: theres this message on my phone that keeps popping

its ur sim which got damaged no issue in handset