How does the Trent 800 deliver engine data?

In numerous report, for example [1], it is reported that the engines of the missing MH370 was sending engine data to the ground:

"...data automatically downloaded and sent to the ground from the Boeing Co 777's Rolls Royce engines as part of a standard monitoring program"

What I've failed to find is some description of how this system works. Is this an RR-only thing, or is it a standard way of transmitting engine data from planes?

[1]http://www.nbcnews.com/storyline/missing-jet/report-missing-mh370-flew-four-hours-after-known-position-n51536