Yea, I'll have to try it on a pots line somewhere again. Remember that it did pick up call/caller id/time twice off the 3600HGV. Once when first connected and once again 8 days ago (after being connected and up for days). My supposition has always been that one or both devices are close to some threshold. Olympia is out of business so no hope there for information on internal implementation or updated firmware. I figured I start by comparing/checking the 3600HGV output. Against mfg specs and against what I likely had with POTS and go from there. If it wasn't within mfg specs or borderline then I could probably get AT&T to just swap it try my luck with the replacement. Who knows, it might be detecting ring and then bailing out because of some unexpected data or options following. It does irk me a bit that I can't seem to get specs on the AT&T supplied device interface meant to be connected to customer equipment. sigh

If I go to another device it looks like either the Telnote or Brighter ID'er. Leaning towards the Brighter ID'er since it's LED and Telnote looks to be LCD. ...neither come with a blue display...