This caller (which no doubt displays a fake number... particularly obvious since it's got a 555 prefix) plays the trick of calling twice in quick succession, so that (for instance) while my line #1 is engaged from the first call, it reaches my line #2 (rollover number) and/or my forwarding number with the 2nd call. This tactic was used recently with an unlisted number calling me; I've blocked those, so now I see a fake number instead. I've got to research whether my Ooma Second Line feature (basically a rollover number I'm given for free) can be assigned the same blacklist and blocking preferences as the first one.
This caller (which no doubt displays a fake number... particularly obvious since it's got a 555 prefix) plays the trick of calling twice in quick succession, so that (for instance) while my line #1 is engaged from the first call, it reaches my line #2 (rollover number) and/or my forwarding number with the 2nd call. This tactic was used recently with an unlisted number calling me; I've blocked those, so now I see a fake number instead. I've got to research whether my Ooma Second Line feature (basically a rollover number I'm given for free) can be assigned the same blacklist and blocking preferences as the first one.
To add to my message above: I'm now just blocking the whole 555 prefix (in conjunction with my area code; i.e., 650-555-xxxx). It's almost guaranteed to be fictional as a received call. My Ooma blacklist allows me to use a wildcard to do that (650555*). The second-line blocking I mentioned above wasn't really the issue, since I hadn't blocked that specific number before. (I had blocked a similar 650-555-1236 number recently, which was used to spam many, many people. So I'd thought the blocking was defeated by the rollover, when I saw the 555 prefix.)
I'm adding this information here in case someone else with Ooma (or similar service or device) is faced with the same issue. BTW, Ooma only includes the second-line option with its Premier service, which costs about $10/month extra (and I do subscribe to that). Just wanted to clarify that from my previous message, since I can't edit that posting.