Nwsrg...
As far as I know (and Id put a b***ock on it) the only way chief could have known the type of fone offending down the the back is through a cheeky bluetooth scan.. Theres no way anybody could possibly know what phone or network was active... simply set your bluetooth id to, 'Turn ya fone off skipper' and see if the shout on the PA reflects that...
Only joking.. Fones off in dep lounge is the safest bet.
DPT