: Standard firmware enforces carrier locks and regional frequency blocks. Custom firmware can bypass these to allow a device to connect to any network globally.
: Advanced firmware, such as those used in projects like OsmocomBB, allows users to "see" the raw data coming from cell towers. This can help detect "Stingrays" or IMSI catchers that are attempting to intercept calls. gsm+secret+firmware
In summary, while "secret" firmware was once a standard for cellular privacy through obscurity, it has become a primary frontier for mobile security research. The independence of these systems makes them powerful but also potentially dangerous if left unaudited. : Standard firmware enforces carrier locks and regional