[asterisk-users] how to block spammer calls

[Anselm Martin Hoffmeister]

Am Samstag, den 05.01.2008, 11:58 +0530 schrieb ram:

>  
>  
> Hi
>  
> I understand what you are saying.
>  
> so once we see he is not input the pin more than 2times
> he will be blocked for hour ( i will run cron job, after one hour
> release them)
>  
> is this a good idea.

Hi Ram,

I do not think that is a good idea. 2 tries are not much on the one
hand, and on the other hand, your competitors probably know how to fake
CALLERID, so once they find out their calls are not answered anymore,
they can just set another CALLERID and dial in again and again. If they
really want you to pay for useless minutes, the only thing you could do
against it (if you do not want to block everyone) is requiring your
customers to register the phone number from which they will dial in, and
throw away (by not answering) any other calls.

Using cronjobs is possibly a bad idea because you create load spikes, if
e.g. 5000 asterisk -rx commands are issued within a few seconds. A
better way to implement it would be storing the last unsuccessful
authentication system time and wrong PIN count for each CALLERID, and
block the ID if a count of >=3 happened less than 1800 seconds ago or
similar. This blocking would need appropriate dialplan logic. I think
there is soem material about astdb, time and blocking in the examples
section on www.voip-info.org; if you cannot build something on your own,
(as mentioned) you might want to pay someone some bucks for implementing
it.

In Germany I _think_ calling 0800 numbers for abuse can be sued against,
on the grounds of tampering with phone infrastructure. If the same
number calls in more than 100 times a day or so, you could probably ask
the number provider to close the caller's account (and if they will not,
you can still sue). If the person calling your 0800 is a competitor,
there is a law called UWG here (law against unfair competition): It
probably allows you to sue them for compensation of minutes and blocked
lines, but you would need to ask a lawyer for details - and any other
country will see a completely different solution anyway.

BR
Anselm