1. Install wvdial. Note that the current version of wvstreams (4.6.1-9), a dependency of wvdial, has some sort of showstopper bug that makes wvdial crash when connecting with the following error:

   wvdial: utils/wvtask.cc:304: static int WvTaskMan::yield(int): Assertion `*current_task->stack_magic == 0x123678' failed.
   
   

   A current fix is described here and here. An archive with a PKGBUILD and the relevant patches can be found here.
2. Edit /etc/wvdial.conf as follows¹:

   [ Dialer Defaults ]
   
   Init1 = ATZ
   Stupid Mode = 1
   Dial Command = atdt
   Carrier Check = no
   
   
   [ Dialer Verizon ]
   
   Modem = /dev/ttyACM0
   Baud = 100000000
   Phone = *99***3#
   Username = 1
   Password = 1
   
   

3. Stop NetworkManager or similar.
4. Run wvdial Verizon as root after connecting the modem.
5. Enjoy!

linux