In a channel switching system, first and second stations are normally interconnected through first and second regular channels and switched to fallback channels established by a public switched network in the event of a fault in the regular channels. In the event of a fault in the regular channels, a tone generator at the first station transmits a tone signal to the second station through the first regular channel. A signal-to-noise (S/N) ratio detector at the second station receives it and derives a S/N ratio of the first regular channel, and transmits a S/N ratio indicating signal to the first station. A switching controller at the first station receives it to detect when the S/N ratio of the first regular channel is higher than a reference to interpret that the first regular channel has been recovered. Upon recovery of the first channel, a tone generator at the second station returns a tone signal to the first station through the second channel. A S/N ratio detector at the first station receives it and derives a S/N ratio of the second regular channel. The switching controller at the first station detects when the S/N ratio of the second regular channel is higher than the reference and switches the first station from the fallback to the regular channels and notifies the second station of this fact to allow it to be switched from the fallback to the regular channels.