1100 insert sim problem - Nokia 1100

SOURCE: what should i do when 1100 cell shows insert sim

the pins that touch the sim card could be lose or the sim card might be bad, try pulling the pins on the phone up carefully just a little so its a little more thighter to inser the sim card, then try again, also try another sim card if it doesn't help.

SOURCE: insert sim

try cleaning the metal contacts in the phone with a small wire brush or an old toothbrush with switch cleaner (available from most electrical shops) that should do the trick, good luck

SOURCE: MY NOKIA 1100 SHOWS INSERT SIM EVEN IF I INSERT WORKING SIM

Hi,
This can be caused if the sim slot in the phone is loose, this can be fixed very easily by taking it to a repair shop and having them change the sim holder.
Hope this helps, Joe

SOURCE: Second Hand Nokia 1100 - SIM CARD Problem

all you have to do is clean out the phone insert the sim in correct way, if this does not work then get a new sim or excahnge the phone for a new one