Connect WAN 3G

A number of DIGI Connect wan 3g have been installed by my division. I was not part of it.  My group has been called because a lot of these units are not operating while others are.  We are not experience with these devices.  So far, yesterday we applied a post upgrade and a firmware upgrade to a couple of these units. The logs don't help much so far. For the ones thatt are down we have to power them up physically( disconnnect the power cable and reconnect).
Also i notice that thre is not security on them.  

Updates applied: ver. EOS firmware
                             Connect WAN 3G 32MB POST Firmware

My questions is why some of the units are workings and others are not.
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Miguel Angel Perez MuñozCommented:
Maybe problem are in SIM card. Try change a SIM that work on a 3G modem with another that don´t work.
ShenAuthor Commented:
I will look into your suggestion. Out of 257 units , about 80 are not working.  That will mean that there are a lot of sim cards taht are  bad.
Miguel Angel Perez MuñozCommented:
SIMs maybe not activated by operator for example. Changing SIM discard 3G Modem failure.

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