If it was "All lines busy" then perhaps it was BT's fault and
all lines were busy
, but more likely the Exchange was !! That's not unusual for BT to do that at various times of day, though personally I have never had a problem with 18866 yet (touching wooden cabinet), but pigs DO fly so I await my first !
I don't often get a problem with OneTel, yet over the last year or so I've had a few, and I'm not talking about Admin (had some of those), just connection type problems, but I still find them very good overall.
I have looked at Telesavers for my overseas calls, as it seemed cheaper than 18866, but the 0844 on BT is charged /min unlike 18866 /sec overseas call charges, even if they do add a 1p connection charge.