L(x[:y][:z]) - Limit the call to 'x' ms. Play a warning when 'y' ms are
left. Repeat the warning every 'z' ms. The following special
variables can be used with this option:
* LIMIT_PLAYAUDIO_CALLER yes|no (default yes)
Play sounds to the caller.
* LIMIT_PLAYAUDIO_CALLEE yes|no
Play sounds to the callee.
* LIMIT_TIMEOUT_FILE File to play when time is up.
* LIMIT_CONNECT_FILE File to play when call begins.
* LIMIT_WARNING_FILE File to play as warning if 'y' is defined.
The default is to say the time remaining.