Brittle and silently hackable.
Hey, let's put micro electronics in a box with wires wandering outside. This box is part of BTs line. If a nasty spike comes in at the moment it might fry a router or possibly a phone handset. In the future you're waiting for Bombay to add you to some invisible queue.
Now there's an internet box with all of the appeal and security track-record of IoT. Made in China and up-datable down the wire.
Biting the hand that feeds IT
