How can a non-default Android app send SMS automatically without user...

plumb_pete

I’m developing an app that needs to send an SMS automatically when a certain event happens (e.g., a user action). The user should not have to interact with the phone after the event – the message must go out silently in the background. The app is not and cannot be the default SMS app. I’m using SmsManager.sendTextMessage() from Kotlin (called via Flutter’s MethodChannel). It always fails with RESULT_ERROR_GENERIC_FAILURE . The SMS never gets...

Originally asked by Mikias Gebresilasie on Stack Exchange (stackoverflow) (CC BY-SA 4.0).

uphilltech

Great question — answering as the UphillTech team:

You don't need to be the default SMS app to send — SEND_SMS runtime permission is enough. Default-app role is only required for receiving/aborting SMS or writing to the SMS provider. So a non-default app with SEND_SMS granted can send fine; GENERIC_FAILURE is almost always one of these: Wrong SmsManager subscription on a multi-SIM device. SmsManager.getDefault() is the usual culprit. On API 31+ use the system service and pin the subscription: SmsManager sms = context.getSystemService(SmsManager.class) .createForSubscriptionId(subId); // subId from SubscriptionManager.getActiveSubscriptionInfoList() // On older devices: SmsManager.getSmsManagerForSubscriptionId(subId). getDefault() is...

Full answer by Андрей Джабаров: https://stackoverflow.stackexchange.com/a/79954234 (CC BY-SA 4.0).

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