You dont say who your Service Provider is, but presume its BT, if you have a noise problem then the line testing OK is quite common, it doesnt mean the line isnt faulty, but what it does mean is that if you proceed to get an engineer call out and by the time the engineer comes out the noise has gone, or the problem was on whats called end users own wiring then you would be charged for the abortive call out (£115 or whatever it is) the £99 is only if you want the engineer to repair/replace your faulty wiring/sockets etc......if your line isnt wired in the 'standard' way through a NTE5 type master socket, with all other sockets being wired from the removable consumer panel then you shouldnt be charged if the problem is wiring/sockets but the engineer would disconnect them,not repair or renew them (unless you wanted to pay the time related charge to do so (thats where the £99 comes in) but if the problem was a telephone instrument, adsl filter or anything else that can easily be dis-connected you would be charged, noise problems can be a concern though because if the noise isnt there when the engineer calls and books the fault off as 'right when tested' then a charge is usually raised....If you look in your phone book, about page 6 or 7 there is a guide on how to 'prove' a fault either internal (your problem) or external (bt's problem)