So, we poked around and could not find a "ringtones.xml" on the snomONE SoHo build to alter. Found a 'modified for 'intercom use' file here:
http://forum.snomone.com/index.php?/topic/3646-4104013-linux-intercom-not-working/
We placed it in the HTML directory, as suggested in the thread above, and re-started. (No idea how a current snomONE build (-5021) will refer out to that 'ringtones.xml' file.)
Double checked that Polycom xxxxx.cfg file tells the set to use the right ring behavior in response to an "Auto Answer" in Alert-Info, as noted in many places.
Still, no joy.. Sets just ring away like normal. Suggestions?