RoamGuard

RoamGuard is a mobile app that predicts and prevents accidental roaming and costly data leakage when you travel or live near borders. It monitors your SIM/eSIM status, carrier changes, and radio conditions to detect when your phone is likely to latch onto a foreign network or switch to an expensive roaming profile. You set rules like “block data if not on home carrier,” “allow only messaging apps,” or “cap roaming spend at $10,” and the app guides you through the exact OS steps needed (since iOS/Android restrict direct control). It also keeps a trip timeline with reminders: enable eSIM, download offline maps, switch preferred network type, and verify APN settings. Realistically, it won’t eliminate all roaming risk—OS limitations and carrier quirks exist—but it can dramatically reduce the most common, expensive mistakes.