I found a topic in the german Ubuntu Users Wiki describing your problem. They suggest commenting out a range of lines in /etc/ppp/options:
lcp-echo-interval 30 # range start
lcp-echo-failure 4 # range end
From my experience with different dongles and Ubuntu versions I would like to propose another solution:
Buy a MiFi or Huawei E5, those are mobile hotspots providing internet access for 3 to 5 devices at the same time. Everything that needs to be configured will be done on the hotspot and you simply connect via WiFi or USB.
If your notebook is equipped with a SIM slot and antennas buy an internal modem card, I never had issues with that.