Gammu-1.24.0 still depends on bluez-libs, althought bluez-4.* has been unmasked, causing a conflict.
What conflict? Can you post the emerge output that proves it? FYI, the bluetooth dependency atom of gammu is bluetooth? ( || ( net-wireless/bluez net-wireless/bluez-libs ) ) so I don't really see how it can conflict with net-wireless/bluez since it is the first options it considers.
Sorry for the very long delay, I've been away... I'm sorry, it seems that I made a blunder here... I based this bug report on what portage told me, and the output of equery depends bluez-libs the latter of which, in this situation, gives false positives.