[asterisk-users] Checking blank CallerID in Dialplan

[John Novack]

You will find there are an infinite number of bogus CLID's that these 
scumbags use to thwart screening. Such things as invalid NPA, invalid 
office code are common. Blank is seldom used any more.
Here in the US at least, even with the do not call list ( federal ) and 
various state do not call lists, they still squeek through. Part of the 
stupidity of the DNC list ( federal ) is that there is a charge to USE 
the list so the bottom feeders don't bother, and with some providers 
allowing phony CLID there is little hope.
What we do is screen for the private, blocked, etc, then capture the 
number and name into a MySQL database. A php script then can display 
that, and allow for setting a field to block if it ever comes through 
again. In the dialplan, if the number comes through but NO name, they go 
to a VM box that allow legit callers to leave a message, the rest simply 
hang up. Even valid numbers of callers we want no conversation with can 
be blocked as well. The script also allows entry of known undesirables 
to be entered.
Once a number is blocked, they are routed to an intercept recording that 
APPEARS to be authentic, and often that is enough to discourage further 
calling.
Also be prepared for the infrequent call that is missing any CLID.
You are only limited by your imagination, and the undesirable callers 
tenacity to outfox your scripts.
Be prepared to continue to change and improve your efforts.

John Novack


Myles Wakeham wrote:
> I am trying to implement a change to our Dialplan that will thwart 
> tele-spammers that are calling us with blanked out caller ID.
>
> The caller IDs seem to vary between originating callers when they block 
> caller ID.  I've seen the following:
>
> "anonymous"
> ""
>
> So I'm checking for these.  However recently one company seems to be 
> bypassing this, so what I wanted to do was implement some logic that 
> checks for actual numbers in the caller ID.
>
> We have a couple of different SIP providers for incoming calls.  Some 
> prefix numbers with a +  and others don't.  But I'm logging incoming 
> calls that are getting through our tele-spam filter and it seems that 
> they are blank, but I suspect they contain empty spaces which is why our 
> matches don't work.
>
> Does anyone have some sample DialPlan code that they are using to thwart 
> incoming calls with no caller ID?  I was thinking of maybe converting 
> the caller ID num to a numeric value and testing for 'not equal to 0' 
> but that won't work with the + prefix.
>
> All suggestions greatly appreciated.
>
> Myles
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-- 
Dog is my co-pilot