Synopsis:

       SMtrace(vox_chan,on_off)

Arguments:

       vox_chan – The voice channel

       on_off – set to 1 to turn event tracing on, 0 to turn it off

Description:  This function allows for event tracing to be turned on or off for a particular vox_chan.       If turned on then all events on the specified channel will be logged to the system trace log.

Returns:  Return 0 on success or -1 is bad channel is specified.