Is my Freeview box going to call the RAF too?

There have been two incidents of Freview boxes calling in the RAF:
Digital box triggers 'SOS' alert
(15 Jan 2006)
Freeview box sparks rescue mission (14 Feb 2006)
It's unlikely to happen to you, but it's best to avoid setting your Freeview box to set your RF modulator to use "channel -23" or "channel 233"!
(UK TV frequencies are divided up into 8Mhz blocks, with the first, C21, starting at 470MHz. Using a value of -23 (or perhaps 233) into the equation generates just about the right value to your TV sound into an emergency signal, where f(audio)=-23*8+302+3.25 - this is within 0.25Hz of the 121.5 MHz distrss frequency.)
Help with Television sets?