Blacklisted numbers are not enough

[apitsos]

Hi there!

I do have a problem with an installation, where we have inserted a really big list of numbers to blacklist. I have noticed that numbers we have added in that list are not blacklisted and we accept calls from them. I also have noticed that when I browse the blacklisted numbers (from "Settings" > "Blacklisted Numbers") the pagination goes up to page #100 and not further. But I have inserted more numbers than that.

1. Is there a limitation on the number of the blacklisted numbers that someone can add?
2. Is there any possibility a number that is in that list not to be blacklisted and the system accepts a call?
3. Does it make sense to have a number added with four (4) different ways in order to catch it (local number, country number without zeros, country number with two zeros, country number with plus sign)?

Regarding the question number #3 I would like to give some more clarifications:
On that PBX I have more than one trunk, from more than one provider from Greece. Some SIP providers are providing the numbers without the country code, some of them provide the full numbers (including the country code). So, let's suppose we want to block the Greek number 2101234567. In order to make sure that it will be catch on any case I add the following entries in the blacklist:

• 2101234567
• 302101234567
• +302101234567
• 00302101234567

I hope for having answers on all the above questions from an official representative.

Thanks a lot in advance for your time and support!

 

[NicholasP_3CX]

You can use wildcards if you want.

*2101234567 and this will take care of the prefixes at the beginning.

You can also use wildcards like this *210* . However I would be very careful with this as this would block ANY number that contains 210 in it.

 

[apitsos]

Hi @3CXNP!

I didn't know that function. Thanks a lot for the info. Of course someone has to be careful with the use of wildcards. It's clear enough. But as prefix, it reduces the number of my entries to 1/4, because I used these four forms in order to make sure they will be blacklisted.

No, would you be so kind to let me know if there is really a limitation on the number of the blacklisted numbers that someone can add in a 3CX PBX? Is it true that this 100 pages cannot go further?

 

[NicholasP_3CX]

Yes, there is a limit of 100 pages, as the PBX will need to process this list each time there is an incoming call in order to filter any unwanted calls. The longer the list, the longer it takes for any incoming call to establish, so we need to limit this for performance reasons.

 

[Thomas Materne]

@NicholasP_3CX Could a solution be the use of the CFD? And making an application check an external blacklist? Or would that be not supported due to the bigger amount of data

 

[NicholasP_3CX]

@Thomas Materne that could also be a solution!

 

[apitsos]

Hi @NicholasP_3CX!

Thanks a lot for providing this information. I also thanks @Thomas Materne for his idea.

I suppose I am covered 100% and we could consider this thread as "solved".

 

[AWS2P]

Hi,@apitsos
What is your need to blacklist so many numbers? is there a problem in Greece with unwanted calls?

 

[apitsos]

Hi,@apitsos
What is your need to blacklist so many numbers? is there a problem in Greece with unwanted calls?

Exactly! It's unbelievable how annoy they can be and how much disrespect the law. Think about that I live in Germany three years now and they keep calling me all the time for electricity/energy offers, Internet connections, mobile phone connections, beauty institutes, polls, cabled television, loans and much more! Not to mention the law offices that are trying to collect money on behalf of the providers or the banks.

I believe only a Greek can understand that. But think about living in Germany and calling you all the time for offers regarding services that can be delivered only in Greece. Even if you tell them that you don't live in Greece and you are not interested, they don't believe you because they call to a land line (of course they have no idea what SIP is) and of course they don't remove your number from the lists, no matter of how many times you request it, according to the law.

So, if I want to keep the Greek numbers for communication with my clients in Greece and my relatives, I have to blacklist huge lists. Some of them I found them on the Internet, but most of them are coming from me. After an annoy incoming call I have to blacklist the number. It really helps, as I have minimized a lot the annoy cold calls.

It's so ridiculous...!

 

[leejor]

With those types of calls, blacklisting only works if they don't constantly change their number(s). Many countries forbid spoofing, but a lot of SPAM calls originate from countries where just about anything goes.

You're also being reactive, only blocking after they have called. You could be proactive, and at least block the Robo-calls (non-human callers), by having the caller enter a digit, for the call to continue, though an IVR. Provide something informative in the greeting message, and legitimate callers won't think twice about it.

 

[apitsos]

HI @leejor!

Thanks a lot for your input. I have several numbers and the ones that are for business purposes are landing to a grreting message and IVR functionality.

But I also kept the phone number I used to have at home in Greece. And when they call on that number for polls, electricity companies, providers and all these useless cold calls, then it gets really frustrating.

 

[AWS2P]

for private calls, i used in the past a way not so elegant but filtering all unwanted calls.
My way was to ask for a code to be done from callers, only the ones i've given the code could really ring my phone and i new it was family or friends.

Now in France we have also a Free government service http://www.bloctel.gouv.fr/ you just need to register your line numbers for free for 3years.

 

[leejor]

Since you already have an IVR in play, you could make use of the ability to ring an extension directly. So rather than a code, as such, simply give legitimate callers your phone number along with the extension number to dial in the IVR. Of course, don't tell callers that they can dial an extension directly, and if they press a single digit, have it end the call, or create more hoops to jump through. The most persiatant could be sent to voicemail, that is never returned.

 

[The Keymaster]

This brings to mind devices in the USA like the tele-zapper device that played the SIT tone combination for "disconnected' when answering every call. It was popular in the 1990s. The robodialling equipment and call center autodiallers would hear the 3 beep tone and disconnect automatically.

 

[leejor]

A friend of mine still does that as the "intro" on his answering machine message. I'm not really certain that it has any effect these days.