Changing your ROM (generally) does not mean you changed/updated your radio, and you probably didn't if all you did was flash a different ROM. To view your baseband (radio) version, have the phone powered off, hold down the volume down button, and power on the phone, to get to the bootloader screen, which will show what radio you currently have. Also, you can view your baseband in the about section in settings on your phone while powered on. The menu options may be slightly different depending on the ROM you are using, but go to Settings, About, Software info, More, and view your Baseband.
Current device: HTC One M7