Gammu doesn't work with ussd request

Question

I want to use gammu for using my web-stick, i. e. getting information about my account and loading up my account. In other words I’m interested in sending USSD-requests and reading the answers I get.

Info:

• system: Lubuntu 16.04.2 LTS (64bit)

• Bus 001 Device 016: ID 12d1:1001 Huawei Technologies Co., Ltd. E169/E620/E800 HSDPA Modem

• usb-modeswitch: installed

• gammu 1.37.0-1build1: installed

• .gammurc in home directory with

   port = /dev/ttyUSB2 
   model = 
   connection = at
   synchronizetime = yes
   logfile = 
   logformat = nothing
   use_locking = 
   gammuloc =     
  

When typing in sudo gammu -c ${HOME}/.gammurc getussd "*100#" (checking my credit balance) I get something like

no feedback within specified time. Timeout. Possibly phone disconnected.

Yet my web-stick is connected. The same happens with sudo gammu --getallsms.