This article will show you how to get wvdial from Ubuntu LiveCD and install it on a real Ubuntu. You  exactly do not need internet connection to do all of this. This is applicable to any other Ubuntu derivative such as Linux Mint, because they all already included wvdial and its dependencies on LiveCD. Important: wvdial from Ubuntu 14.04 32 bit must be installed in Ubuntu 14.04 32 bit too, otherwise your system can be broken.

The problem when you are using USB modem in Ubuntu, is, sometimes you will need wvdial but wvdial itself need to be installed first. Fortunately, Ubuntu included wvdial in its official ISO since long time ago. Further, it means wvdial is available in Ubuntu LiveCD but it is not when Ubuntu have been installed. In LiveCD, just command sudo apt-get install wvdial and you install it completely without internet. Yes, Linux Mint has same behavior too. It is probably a secret only few people know. To install it, just insert your Ubuntu CD (same version, same architecture) and command apt-cdrom it to be your additional repository.