I have a Pantech UML295, and is listed as compatible.
https://doc.pfsense.org/index.php/Known_Working_3G-4G_Modems
I have followed these instructions per the compatibility list:
https://doc.pfsense.org/index.php/Verizon_UML290
As well as I tried this:
https://doc.pfsense.org/index.php/Verizon_UML290
I know the modem connects to verizon, thats been tested on a laptop.
Log results
[Opt5_link0] CHAT: The modem is not responding to "AT" at ModemCmd: label
[Opt5_link0] MODEM: Fail to open serial port /dev/cuau0 on speed 115200
[Opt5_link0] MODEM: chat script failed
Link Type: PPP