Message delivery to a device that is switched off or has a depleted battery is contingent on the messaging system in use. Typically, when a mobile device is unreachable, messages are stored temporarily by the service provider. These messages are then transmitted to the recipient’s device once it is powered on and reconnected to the network. The duration for which messages are stored varies depending on the specific service.
Understanding how messaging services handle undelivered messages is important for efficient communication. It ensures that information is not permanently lost simply because a device is temporarily offline. Early SMS systems had limited storage capacity, meaning undelivered messages could be lost if a phone remained off for too long. Modern messaging apps generally offer more robust storage and delivery mechanisms, improving reliability.