Thanks,
I've now merged it, despite it is untested.
I don't think it can seriously break any existing functionality... and if we add some code for a feature that was missing before, having a (possibly) still buggy implementation doesn't hurt either.
It would be great if somebody could test the correct timezone setting and the VPF functionality in general.
One way to test this (and continue to test it in the future) is to write a test that uses hard-coded TPDU's or CP-DATA blocks (preferrably captured from real-world SMS) and feeds them through our code and checks if the result is as expected.