Do Not Adjust Your Set: The obvious canonical example is the Emergency Notification System, run jointly by the Watch Constabulary and Emergency Management Authority, which can send out a signal across the IIP mesh network preempting every device to deliver an emergency notification. Subverted inasmuch as it can be overridden freely at the receiving end, on the grounds that if there’s a gorram emergency going on, people might need to use those devices.
(There is also is counterpart, the Emergency Monitoring System. Separate from the basic functionality in which devices that perceive an emergency happening locally will report it of their own volition, the EMS permits a code to be sent out instructing all devices within a specific area to activate all their sensors and report what they perceive to the WC/EMA. Again, this is optional functionality – no-one has to participate for obvious privacy and property reasons – but rather depends on the authorities being trustworthy and individuals being mutually responsible citizens…)