I always thought Gammu to be workaround for phones whose vendors do not provide software for your favorite operating system. We try to do our best job to work with variety of phones, even though this is hard and never finished job.
However today I was really surprised to find out that some phone vendor built their official application for managing phone on Gammu. The application is of course closed source and available only for Windows, but this does not change anything on the fact they use it. They seem to have modified code slightly, adding some new functions and removing others, separated the code to several DLLs, however I'm 100% sure it is Gammu as they use some unique (read awful) things we have in our code.
I'm not going to disclose their name right now as I want to give them fair amount of time for reaction on my asking for sources. But you will for sure find more information later in my blog.
PS: Gammu is of course not the only free software used inside this application, you can find more there (and you will find there more than I did if you will look longer than few minutes I spent on examining rest of code).