Normally, long-distance calls were billed locally. Since the "trick" required a long-distance call to be placed in order to connect to the remote switch, it would be billed as usual. However, there were some types of calls that had either no billing, like calls to directory service, or for which the billing was reversed or billed to another number, like WATS lines (area code 800 numbers). By dialing one of these "toll-free" numbers, the caller was connected to a remote switch as normal, but no billing record was made locally. The caller would then play the 2600 Hz tone into the line to return the remote switch to on-hook, and then use a blue box to dial the number to which they really wanted to connect. The local Bell office would have no record of the call.