Checking my WWAN card on a ThinkPad T420

How do I issue that from within OpenWrt?

Install picocom then open one of the ttyUSB or ttyACM devices from the card. Usually the number 0 device is the one which accepts AT commands.

Or on Windows install the Verizon driver not the generic one it should give the most control of the card. It needs to be set to GSM or "global" mode instead of CDMA. Back in those days CDMA 3G service was subscribed by setting up the ESN or MEID with the carrier. A SIM card was not used.

I'm looking at minicom which I just installed under OpenWrt but have no idea about how to open a ttyUSB or ttyACM device.

On the [configuration] screen, I don't know whether to go into the Serial port setup or Modem and dialing