The clocking parameter on analog boards has only one purpose for now,
improve quality and reliability for FAX expedition/reception. The intend
of this parameter is to synchronize the clock of the analog board on which
one or more FXS port(s) is hooked to a FAX device, with the clock of the
digital board that will be used to route FAX between the gateway and the
PSTN world.
There are two possible settings for this parameter: