I recently installed a Sierra Wireless EM7455 LTE card inside a new laptop, and directly after inserting the new SIM card, Windows 10 displayed “No Service” before eventually showing an error about a locked SIM card. It turns out the problem had nothing to do with the SIM card.
To troubleshoot, I went into “Network & Internet Settings,” selected “Cellular,” and then clicked the “Change Adapter Settings” link. This brings up a window of all network adapters, and so I right clicked on the Cellular/Sierra Wireless adapter and selected “Diagnose.” The error message displayed was:
Enter a SIM PIN2 to unlock the mobile broadband device
The mobile broadband device is locked with SIM PIN2. Contact your mobile operator for assistance with unlocking the device.
My cellular provider confirmed that the SIM card issued was unlocked, so this problem initially perplexed me.
I then recalled my general distrust of the device drivers Windows 10 automatically installs and tried to download updated drivers from my PC manufacturer’s website instead. Immediately after upgrading those drivers, my cellular connection showed “Disconnected” (with 4 out of 5 bars) instead of “No Service.” A simple click of the “Connect” button and I was successfully online.