CID Blacklist

[endu.]

Hi 3CX,

Is there a supported way in 3CX V20 to prevent users from making outbound calls to specific telephone numbers?

We already use the CID Blacklist, which works well for preventing blacklisted numbers from calling into the system. However, we also need those same numbers — or a separate list of numbers — to be blocked from outbound calls.

Our use case is a client that carries out legitimate outbound calling. If a customer asks not to be called again, we need to ensure that number cannot subsequently be dialled by any user, including if an agent manually enters the number on their desk phone.

Ideally, we are looking for one of the following:

• An outbound Do Not Call / blacklist feature.
• A way of making the existing CID Blacklist apply to outbound calls as well as inbound.
• An outbound rule that can explicitly reject/drop calls to specified numbers.
• An API-supported method so that our own CRM can maintain the suppression list in 3CX.

I have experimented with creating an outbound rule matching the destination number and routing it to a dummy SIP trunk, but this doesn't seem like a particularly clean or reliable solution.

The important requirement is that the restriction is enforced at PBX level, rather than only within our Software, so manually dialled calls are also prevented.

Is there a recommended/supported way of achieving this in V20?

Thanks.

 

[Charles_3CX]

Currently, 3CX V20 does not provide a native outbound Do Not Call/blacklist feature.

The CID Blacklist applies to inbound calls only, and outbound rules in V20 do not provide an option to explicitly reject/block matching destinations.

Therefore, there is currently no supported PBX-level method for maintaining a list of numbers users are prohibited from dialling. If this is required for compliance purposes, the restriction would need to be enforced externally, for example at the SIP provider level.

 

[endu.]

Thanks for confirming.

In that case, could I put this forward as a feature suggestion for 3CX V20?

It would be extremely useful to have an Outbound Do Not Call / Suppression List, ideally either extending the existing CID Blacklist or providing a separate outbound blacklist.

For organisations carrying out outbound calling, this is an important compliance safeguard. If a customer requests not to be contacted again, administrators should be able to add their number to a central suppression list and have 3CX prevent all users from dialling it, regardless of whether the call originates from the 3CX client, CRM integration, or is manually dialled from a desk phone.

Ideally this would include:

• A centrally managed outbound suppression/blacklist.
• An option to block both inbound and outbound, or outbound only.
• Number normalisation so 07..., +447... and 00447... representations cannot bypass the restriction.
• An API endpoint so external CRM/compliance systems can automatically add and remove suppressed numbers. (future)
• Logging showing when an outbound call was prevented because the destination was suppressed.
• An appropriate message/reason shown to the user when the call is blocked.

Having this enforced directly by the PBX would be considerably more robust than requiring every organisation to implement the same compliance control independently at CRM or SIP-provider level.

I think this would be a valuable addition to 3CX, particularly for contact centres, sales organisations and any business required to maintain Do Not Call/suppression lists.

 

[Colorado VoIP]

This method may not be supported, but in your outbound rules you can define the number you want to block dialing in your "calls to numbers with this prefix," and the end user will hear a recording that 3cx cannot reach the number dialed (or something to that effect).


in the call log you'll see this:


again, this may not be supported, but just make sure the outbound rule is at the top of the list to apply it.

 

[paulodagraca]

Hello endu.,

That does sound like a new feature request indeed.
However, you can use it like Colorado VoIP has presented it.
Also you can combine all the options in one 'outbound' rule, like blocking (example) 0711111111


In this way you will have one number per outbound rule, and keep it all nice togehter.
Just keep in mind that the blocked numbers should be at the top of the list !

Paulo

 

[endu.]

Thanks @Colorado VoIP and @paulodagraca, really appreciate both of you taking the time to help with this.

I can confirm that your suggested approach appears to have worked. We've created outbound rules containing the blocked numbers, left the outbound routes empty, and placed the block rules above our normal outbound routing. 3CX now drops calls to those destinations as intended.

The only significant drawback we've found is the number of entries we can fit into the "Calls to numbers starting with prefix" field. We appear to be limited to approximately 21 telephone numbers per outbound rule.

Our client has been operating for over 10 years, so they've naturally accumulated quite a substantial suppression list, around 150 numbers that must not be called.

As a result, we've had to create 8 separate BLOCK LIST outbound rules just to accommodate the existing suppression list.



So while your workaround has solved our immediate problem — thank you! — I would still really like to see this developed into a proper Outbound Do Not Call / Suppression List feature in 3CX.

For a business with an established suppression list, maintaining 8+ outbound rules isn't ideal, and that number will only increase over time. There's also the potential for human error when maintaining numbers across multiple rules.

A centrally managed outbound blacklist, ideally with API access so it could be synchronised with a CRM, would make this much easier to manage and provide a useful compliance feature.

Judging by the responses here, it seems like this could be a welcomed addition for other 3CX users too, rather than something unique to our particular setup.

Thanks again @Colorado VoIP and @paulodagraca — you've got us up and running with a solution in the meantime!

 

[Colorado VoIP]

it might be substantially easier to block those calls at the sip trunk/provider level then like charles mentioned. in our customer base we have 2 that need to do this, and 1 of them just doesn't want the phones to dial outbound at all (except for emergency 911) and that is much easier. drop them into a dept and block that whole dept from calling.

glad that helped! if you see any odd PBX behavior with calls though you'll have to delete those rules right away.