Eli5: what happens to the things I send when someone doesn’t have service?


When I send a bunch of things to someone and they don’t have service (i.e. on an airplane, in mountains, etc) what happens to all the data that’s been sent? They get everything all at once when they’re back in service, so is the data just like waiting in the network for the signal to be restored?

In: 5

Not an expert on it but, your phone is constantly communicating with cell towers, I think it squawks like every 3 seconds or something. Every cellphone has 2 identifying numbers. The physical number burned into your phone, then your phone number. These two numbers together create your unique ID per say. I’m assuming it just sits in the tower or your phone keeps sending the signal until the receivers device finally starts communicating with the network.

Edit: grammar

It’s like boats in a canal waiting for the lock to open. Once it’s open, the boats go in one at a time.

the message is held by the service provider until the recipient’s device is able to connect to the network again.

Many services, like SMS messages, use a “store and forward” mode of delivery.

When you send a message it goes to a system at your phone provider. They store the message for a moment, figure out who the recipient’s phone company is, then forward it to them. The recipient’s phone company stores the message and looks for the recipient’s phone. If the phone is available, the message is forwarded to the phone. If the phone is not available for whatever reason, the phone company stores the message until it is (or a certain period of time elapses, perhaps a month or more, after which it is deleted) and then forwards it to the phone.

Other services like WhatsApp, Signal, etc. work in a similar way but those respective services (as opposed to the phone company) do the storing of content until the recipient is available.

Certain forms of communication, like phone calls, do not work in this way and instead set up a connection between the caller and recipient so they can have a live phone call. If the recipient is not available, the call does not go through and some alternate action is taken (like forwarding the call to voicemail, providing a “the recipient number cannot be reached. Please try again.” error message, etc.).