I get this announcement on two BT hosted dial up numbers - what the hell does it mean - is it overloaded or an exchange fault so I can complain to someone!
I did and they were as much help as a chocolate fireguard - they told me to ring the ISP which at the time was Fast24 - and getting through to them just wasn't an option.
This recorded announcement comes from the System X Exchange Switch now weather it comes from your local BT exchange (which I doubt) or your ISP switch is a different thing, get in touch with the ISP.