Good evening! You'll love the MiFi Jetpack, I'm just sorry it isn't working yet. Have you had a chance to reach your IT team to see if its been activated? I recommend following the following steps to ensure the SIM card and battery are properly inserted and the MiFi is properly activated, http://bit.ly/LfCEf0. Please let me know if this resolves your concerns.
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This sounds like a wireless password problem. An MiFi should still let you connect to the local LAN even if the SIM is not activated. You might want to try resetting the defaults on your 4620 and try connecting again to confirm. There should be a small reset button underneath the back cover of your MiFi. Press and hold it for 10-15 seconds while the power is on to restore the defaults.
In rare cases the previous model (MiFi 4510L) would lock out users because the password was not resetting correctly. If your MiFi is still not letting you connect after restoring the defaults then I suggest bringing in the MiFi to a local VZW store or sending it back to your IT Dept for support. A bad password problem can only be fixed by swapping out the device for a new one. Since the problem is easily recreatable it should not be difficult to get someone to swap it for you.