That was one of the first ringers made by sencore.
I used it a few times it worked good.
If you don't get no where with manual , check out the CM 2000
if your going to upgrade, has more features like test patterns,Horiz/vert Drive
it was very helpful great Equipment. http://cgi.ebay.com/ws/eBayISAPI.dll?VISuperSize&item=200547700077