Do Not Originate
Do Not Originate: the easiest win in anti-spoofing.
If a number should never place a call, every call claiming to come from it is spoofed. DNO screening blocks those calls with near-zero false positives — no guesswork required.
The basics
What is a Do Not Originate list?
A Do Not Originate (DNO) list is a set of telephone numbers that should never appear as the calling number on an outbound call. The practice grew out of industry efforts to stop impersonation of government hotlines that only ever receive calls — any call claiming to come from one of those numbers is, by definition, spoofed.
For voice providers DNO is unusually attractive: it is simple, deterministic and stops some of the most damaging impersonation scams before they reach anyone. It is not a replacement for analytics — it is the first layer you switch on.
What belongs on a DNO list
Inbound-only numbers
Help lines and service numbers that receive calls but never dial out.
Government & financial
Frequently impersonated agency, bank and fraud-department numbers.
Invalid & unallocated
Malformed numbers, unassigned area codes and exchanges, and unused ranges.
Enterprise-registered
Numbers a business declares it never uses outbound, protecting its brand.
DNO vs. STIR/SHAKEN
STIR/SHAKEN tells you whether an originating provider vouches for the caller's right to use a number. DNO asks a blunter question: should this number originate a call at all? A spoofed call using a government hotline can still carry a signature from a careless upstream — DNO catches it regardless of attestation.
The two controls stack well. VoIP Radar applies DNO screening first, then STIR/SHAKEN verification, then reputation and behavioral scoring on what remains. Each layer removes traffic the next would otherwise have to judge.
Blocking without blocking good calls
FCC rules permit providers to block calls from invalid, unallocated, unused and subscriber-requested DNO numbers, but expect a reasonable process and a way for callers to report and resolve erroneous blocking. Static lists go stale as numbers are reassigned and businesses change dialing habits.
VoIP Radar keeps DNO data current against numbering sources and enterprise registrations, applies it at call time, and logs every block with a reason code — so you can resolve a dispute or answer an inquiry with evidence.
Get in touch
Find out where your network stands
Tell us about your switch and traffic. A VoIP Radar engineer will map your STIR/SHAKEN, RMD and fraud exposure and send a written assessment — free, within one business day.
- STIR/SHAKEN & attestation review
- RMD certification gap check
- Fraud & robocall exposure snapshot
- Deployment plan for your SBC / softswitch