I hate my "small town" carrier they hardly do updates, mainly only if you have the latest greatest phone it seems like, my s5 is still only on Dec security patch!!!
I've got April security patches in the beta firmware I'm using on my phone. At least that is what the phone manufacturer states in the chagelog. There is no way to verify it on my phone. All my updates came directly from the phone manufacturer. However, according to Stagefright Detector, my phone still has three critical vulnerabilities.
Is there anyway to update from a different source then relying on your carrier? I always thought when I pushed the "check for updates" button the phone goes online and checks for updates?
If you Google the model number of your phone showng in About Phone, then you quite probably will be able to find sources to download firmware updates from directly.