Banish junk callers with 3CX

Unsolicited junk callers are one of the banes of modern life. The Direct Marketing Association would like you to believe that the Telephone Preference Service stops these calls. In fact, it really doesn’t. An increasing number of UK-based companies – or certainly those with UK numbers – ignore the rules, and make calls trying to find out if someone’s had an accident, or with official sounding recordings claiming to be offering ‘government information’ about pensions, mis-sold insurance and many other things.

These companies are scum. They don’t respect the law and, while some argue that those making the calls are ‘just doing their job,’ personally I wouldn’t take a job where I was expected to break the law. Given the speed with which the people – if you do get a real person – get off the line, or lie about who they are, the moment you mention TPS, there’s little doubt that they know it too. Would you burgle someone’s house, just because your boss told you to? Not many would, I suspect; and morally, I don’t see much difference as far as cold callers are concerned. Blow the whistle on the company, confront your boss. Don’t just expect to invade people’s privacy and get paid for it. It’s against the law.

Dealing with cold calls

That out of the way, how can you handle these sorts of calls, without inconveniencing your real callers? I use 3CX for my phone system at home, since I have a home office, and there are different numbers for work, personal and an ex-directory one for family; all are, of course, TPS registered, for all the good that it does.

Because there are phones in different rooms in the house, the numbers go to various ring groups, or voicemail, depending on the time of day; so in 3CX you configure the incoming number to direct to a ring group for ‘Business’ during working hours. Outside those hours, I have the same number going to the voice mailbox of the phone on my office desk.

The first thing that comes to mind when you start getting unwanted calls from people is to look on the Extension settings in 3CX; click Forwarding Rules and there’s a comprehensive set of options that can be used to do things like redirect calls to a Skype ID when you’re not there, handle internal calls differently, and so on; I’m using 3CX9, by the way.

Within Forwarding Rules, you’ll see a tab marked ‘Exceptions’ where you can enter numbers that you want to be handled differently, and that’s where you might first think of putting a blacklist of numbers that you don’t want to be bothered by. You can add a number, and tell 3CX to terminate the call – but there’s a slight problem here.

The exceptions here apply to calls made to that particular extension; so, while the phone where I’ve picked up the calls is the one on my desk, they weren’t routed specifically to that one – they were routed to the ‘Business’ ring group. If I blacklist a number on the settings page for my extension, it doesn’t do anything. And, there’s no way to blacklist a number from a ring group, either. So, instead, you have to do things slightly differently. Here’s my step by step guide.

Create a recorded message

I’m going to set up a ‘digital receptionist’ in 3CX to handle these unwanted calls. So start by recording a message that you’ll play to them; I’ve kept mine polite, it says

“Hello. You have dialled a number that’s registered with the Telephone Preference Service. I do not want your call and I am not interested in what you have to say. This call will shortly be terminated. If you believe you have heard this message in error, please email me”

Create a digital receptionist to play the 'Go away' message

When you’re happy with your message, go into the 3CX admin pages, click Digital Receptionist, click Add Digital Receptionist, and then configure it; give it a name that you’ll remember like ‘Terminate – TPS’, and upload the WAV file to use as the prompt, via the ‘Browse’ button. Leave all the menu options blank, and set the timeout to a short period – 5 seconds, say – followed by End Call. Click OK to save all this.

You can check it sounds alright and terminates the call by dialling the number of the receptionist from any phone. You should hear the message played, then the standard ‘Thank you. Goodbye’ from the 3CX sound set you have installed.

Create a dummy extension

Now, you need to create an extension that will act as your junk call filter. It can have any number, but you might like to keep all such things in a particular range. Click Extensions, Add Extension, put in a first name like ‘Spam filter – work’ and make sure that voice mail is turned off for this extension. Click Apply. Do not add this extension to any call groups.

Set your dummy extension to forward to your desired ring group, when not registered

Now click Forwarding rules, and on the ‘Available’ tab move down to the ‘Phone is Busy’ section, which also determines what happens if there’s no handset registered – which there won’t be. So, select ‘Send call to’ and then pick the ring group that you want, in my case ‘Business’. You don’t need to add anything else on this page. Click Apply.

Dialling the extension should now make all the phones in the ring group ring.

Add the blacklisted numbers

Now, go to the Exceptions tab of the Forwarding Rules for the dummy extension you just created. Click Add rule and enter the caller that’s pestering you, set the ‘Received during’ to ‘All hours’ and set the ‘Forward to’ option to the ‘Terminate – TPS’ digital receptionist that you created in the first step.

Add a rule for each number you want to block - all the UK ones here are on Verizon's network

Here you can see that I’ve also put in an option for ‘anonymous’ which will send callers with no id straight to the voicemail for extension 20. One other thing that’s worth pointing out is that the 083 number appears to be a malformed id, possibly from an overseas call centre. But the four other numbers shown in the screenshot – all of which have made unsolicited calls to TPS registered numbers – are without exception in ranges allocated to Verizon UK. Feel free to draw your own conclusions about the ethics of Verizon UK; I know I’m not the only person to have been pestered by lots of their customers making cold calls.

Redirect incoming calls

The final step is to go back to the inbound rules, where your incoming numbers are defined. Find the appropriate entry and in the section where the number was previously connected to your ring group – Business, for my example – change it instead to connect to the dummy Spam Filter extension. Click OK, and make a test call to check everything’s still being routed correctly.

Finally, set the incoming call destination to the new dummy extension, instead of the ring group

It’s worth then adding a mobile number to the blacklist on the extension, and calling from that, to check that it’s correctly filtered out.

And there you have it, more or less; one thing worth mentioning is that the way I have this set up, the incoming calls go directly to voicemail outside office hours, rather than via the filter; I’ve found that the junk callers never leave messages, so it’s not an issue, but you could change that if you want to.

I also have the same filter working on my ex directory number, 24 hours a day now, and a slightly modified version on the public number, which plays a message warning cold callers I’ll be very rude to them, and inviting genuine callers to press a button, which the digital receptionist uses to transfer their call to the appropriate ring group.

Leave a Reply

Your email address will not be published. Required fields are marked *