The tower companies constantly do upgrades to their towers which occasionally means the devices connected to them have to be power cycled to clear the towers cache of old information.
To do this, unplug your device and leave it unplugged.
* If you have a USB cord and/or ethernet cable plugged in, also remove those.
Next, we want to remove the SIM card. DO NOT PULL ON THE SIM. You want to slightly push it in and you will hear a click and then the card ejects, you can then pull it out.
Wait 5 minutes with the SIM out and the power unplugged.
AFTER WAITING 5 MINUTES:
Reinsert the SIM card. You will hear another click as the SIM catches.
Plug the unit back in and give it up to 10 minutes to reconnect.
If this does not get you back online, the next step would be to verify that the APN is set properly on your device. That knowledgebase article can be found here by clicking here.
If at any time you need our help though, please don't hesitate to call or start a ticket. These KB articles are for people who want to do it on their own, but just know we are always glad to help walk you through it if you need our help.