There are several potential reasons for FaceTime call drops, including network issues, device-specific problems, app-related glitches, connectivity or compatibility issues, or advanced settings or features that need further adjustment. To troubleshoot the problem, you can try resetting your network settings, checking for SIM card errors, ensuring both parties have FaceTime enabled, restarting the app, using Siri shortcuts, blocking unwanted calls, or utilizing additional settings and features to enhance FaceTime stability.