Text/SMS messages

[twingo2]

We send hundreds/thousands every day, but how does it work after they leave the phone? And what happens to all those txts that we are told, never arrive? Help!

[evilswan]

well. here goes. you type a text and press send. there is a message centre number stored in your phone, one for each mobile operator, and these act kinda like a mail server on the internet, storing messages and trying to deliver them. so say for example i send a message to tel: 111, this gets sent to mailsever 7688, this server then adds my message to a queue until it can get around to it, then when it's time it sends it to the intended recipient (which will be encoded in the message header). if the recipient's phone is switched off, it adds it to the back of the queue to try later. the reason some get lost is probly because the system has tried to deliver your message a few times, and decided to delete it. it can't try forever, or we'd never get any messages delivered. hope this rather simplified explanation helps.