First, make sure that the APN and PIN settings are correctly defined for your SIM cards. The Track Box will try and connect as soon as it is on, and if the PIN or APN are not properly setup, your SIM card may be locked by your operator.

Open the active Track Box by unscrewing the two golden screws on the bottom with a 4 mm hex key.

Make sure not to lose the O-rings, or the nuts.

Insert the SIM card to the slot until it clicks in to place.

Reassemble the two parts of the Track Box, and fasten the screws. Make sure the O-rings are still in place, do not fasten too tight.

If you are doing this with several Track Boxes at once, make sure that the serial number on the lid matches the one inside the Track Box.

Once your SIM cards are inserted, you can turn your Track Boxes on, the Track Boxes will attempt to automatically set the APN which may take up to 5 minutes on the first connect. If they do not show as connected within this time you may need to Configure the SIM APN manually.