| forgot about SMS delivery receipts. Some operators' short message service allow the sender to request a "delivery receipt". Basically the Short message Centre keeps trying to deliver the message according to various retry rules. It knows once it's been sucessfully delivered to the handset, then stops having to re-try. If a "delivery receipt" is offered as a service, then it can then send another short message to the original sender confirming this. As well as retrying periodiccally, it is prompted to retry if you (re-) attatch to the network (eg turn your phone on, or arrive in a new country). No malarkey going on if the network allows delivery receipts.
Hywel |