Decide what the list should do
The Blacklist module matches caller numbers and sends matching calls to a chosen destination. It also offers an option for calls with unknown or blocked identity. These are different policies: a list of known nuisance numbers is narrower than rejecting every anonymous caller. The official guide uses FreePBX 13 screens; confirm the controls in your installed module.
Before changing anything, write down one unwanted-call example, the affected DID, its time and the business owner for the rule. Decide whether rejection, a brief announcement or a staffed destination is appropriate. A blocked-call destination that routes back to the same inbound entry can produce confusing repeat behavior.
Use the identity actually received
Inspect a recent call record and, if necessary, a short authorized SIP trace. Compare the number received from the trunk with the value presented to the blacklist. Country prefixes and local normalization matter. Do not assume a ten-digit example in an older screenshot describes every country or carrier.
Treat a caller number as a matching input, not proof of who called. A spoofed number can belong to an innocent business. Prefer a narrow rule with an owner and review date over an unreviewed imported list.
Add one reversible rule
In Admin → Blacklist, add the observed number and a neutral description of the operational reason. Record the prior settings before choosing the blocked-call destination. If staff use telephone feature codes, read the actual assignments in Feature Codes; defaults may have been changed.
Use an authorized test number first. Call the public DID from that number and from a separate allowed number. Confirm the first reaches the intended destination and the second still follows the normal inbound route.
Evaluate anonymous calls separately
Do not enable unknown-caller blocking simply because a single spam campaign uses changing numbers. Ask whether customers, hospitals, switchboards or privacy-conscious callers legitimately withhold identity. If the business enables the policy, test a withheld-ID call and make sure the resulting message explains a usable next step.
Run the test through each relevant inbound trunk. Different carriers may represent withheld identity differently; a successful test on one path does not establish behavior on another.
Review mistakes and undo cleanly
The documented statistics view includes calls from before a number was listed, so it is not a count of proven blocks. For a complaint, correlate the call time with the rule activation time and actual routing evidence. Remove the entry, retest the same inbound path and record the correction.
Export only when needed for recovery and protect the file as customer calling data. Review aging entries periodically so reassigned numbers do not remain blocked indefinitely.
Sources & applicability
Primary references for the technical details above. Operational examples and planning checklists are VoIP.info editorial guidance.
Examples require adaptation to your topology. No live PBX or hardware testing is claimed.