S3 resets the lon network. If you find the call light on or non-responsive and the microswitch is good, then the node is bad, order a new board. They are susceptible to noise interference from the 120vac in the gutter. You can easily run new shielded cat 5 and problem will disappear. That crappy flat phone cable is junk and most times the ends aren't properly installed. That's just likely your intermittent issue, just a loose connection. And cat 5 tools and ends are available at home depot.
