Looking through my CDR I just saw two batches of four calls within 2 seconds to the same DID from "2457883364". (245 is an unassigned area code)
Currently I use caller-id filtering to "hangup" calls from this area code.
Presumably the spammer's kit retries calls 3 times before giving up (nice to see such dedication to service :-) ), then tries the same number again about five minutes later.
Ideally I would like a call treatment that:
Is unlikely to cause the spammer to questions their caller id (so they don't change their behaviour),
Costs the spammer money and/or time,
Doesn't cost me anything.
Unfortunately the only call treatments available on voip.ms which don't cost me money are "Hang Up" and "Busy". I'm thinking of switching to "Busy" as this may make a spammer less likely to be realize that they are being blacklisted, and might stop the immediate retries as the spammer's equipment is more likely to understand a busy signal.
Has anybody noticed any downsides to doing this?
My guess is that spammers will retry more often at longer intervals (not so obvious on the CDR), but some hard data would be useful.
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