Previously I had an old HUAWEI E160 I have previously tested the problem with old models like the E160, if you are not Windows uses, is that the drive mounts as a disk drive, and it's really a chore, the (Linux) System so should get that you can dial a modem at the stick.
When I then connected the E303 and wanted me to dial the modem, I was only at a loss, because it did not want to work. Until I found out that the E303 is no longer acting as a modem, but is automatically recognized as a network card and the computer / laptop simply assigns an IP.
The drive works with Ubuntu 4.14 and higher (I have not tested older versions) out of the box and easily installed as a network interface, the dial-in triggers the drive internally here. Really nice that on the IP 192.168.1.1 is directly Manage reaches the router and network profiles, updates, SMS or automatic connection to the router and can store. On older devices for some of these functions always the Windows program was necessary.
All in all, it works great, you just have to know just that it occurs as a network card with DHCP and not more or you can make all settings directly on the stick under http://192.168.1.1 as a modem. On Windows, the program also connects only these IP to stick.
Speed is also great, get over UMTS ca 7 Mb / s down and 2 Mb / s up with Telering in Austria, which are pretty good values.