As an ATCO I have had this happen to me several times (5-6). Of the 2 major events one involved a stuck transmit frequency where most of the western world were entertained to an amusing dialogue about the state of American football for approx 20 minutes before one of the co-respondances noted "Haven't heard much from ATC recently....."
Second occasion was transit from Lands End to Dover. Not too much of a problem for the first half but from SAM to DVR a lot of excitement...
Inadvertantly turned the volume down...
We would have scrambled the UK interceptor force (English Electric Lightnings) but "They'd make an awful lot of noise over London and besides there would be no point until the ac gets to Eastbourne"
A comment made to me in jest by the duty Master controller (we were aquaintances) but the Lightening was rather short ranged and to have scrambled it earlier would have involved also launching a tanker and then all the excitment of AAR in the Dover area.