FreePBX AllowList Caller Module -- to block all but a list of allowed callers

[Stewart1 (Stewart)]

Thanks for the post. I hope that you, with community help, can grow this into a first class spam filter.

@mitchmitchell

Another thing I want to do is figure out how to change the ‘whitelist last caller’ function into a ‘whitelist voicemail caller’ function.

If the rest of the system is working properly, manual additions or deletions should rarely be needed. I’ve not made a manual edit in more than a year.

My (somewhat simplified) flow: If whitelisted, ring phone. Else give IVR challenge and if passed, add to whitelist and ring phone. Else, check number at TrueCNAM and if passed, send to voicemail. Else hang up call. Also, outbound calls add the called number to the whitelist.

See

Of Robocalls and Whitelists

[The functionality of these scripts is largely superseded by the AllowList Module] … of cabbages and kings. I have several DIDs published for business purposes, and as time passes, they become incrementally more prone to robocalls. This is to the point now that robocalls may well outnumber legitimate calls, with some days being intolerable. The FreePBX blacklist is unable to deal with them effectively because there is no consistency to the Caller ID, nor have I wanted to force all callers to n…

Of course, like any filter, it’s less than perfect. It’s nearly 100% effective at keeping unwanted callers from ringing the phone (only 2 in 3 years, caused by spoofs of legitimately whitelisted numbers). And AFAIK, it has never hung up on a legitimate caller. However, a few wanted calls are sent to voicemail (false positives), and some spam ends up in voicemail (false negatives).

I don’t see a good way of greatly reducing the number of false negatives, but the time they waste could be nearly eliminated. Presently, I spend ~20 seconds each, listening to and deleting them. What would help a lot is a combination of voicemail transcription and a visual voicemail system that groups together all messages resulting from the spam filter. A few seconds looking at the screen, you click one button “Filtered messages are all spam” and they disappear.

Most false positives are not a big deal. The caller leaves a message and you call back. Even if you don’t get through, they’re now whitelisted and their next attempt will ring your phone. However, some wanted robocalls are a serious problem, for example, a notification of a possibly fraudulent charge on a credit card. This can be mitigated by requesting that such notifications come by SMS. But if you call a big company, are on hold for a long time and are offered a callback, it often comes from a different number, unknown to you. If that goes to voicemail, you’re screwed and have to start over. My present crude workaround is a BLF key on the phone that temporarily disables spam filtering. When active, it lights up red, so I’m reminded to turn it off after receiving the callback. I hope that someone has a database that could be used to dynamically auto-whitelist these numbers.