Understanding Do Not Originate lists

Do Not Originate (DNO) lists are used by carriers and regulators to prevent spoofing and fraud. A number on a DNO list should not be used as the originating caller ID for outbound call legs. If a call attempts to originate from one of these protected numbers, the carrier may reject that outbound leg.

What is a Do Not Originate list?

A DNO list is a set of phone numbers that should receive calls, but should not be used to place outbound calls or present caller ID. These lists commonly include numbers that are inbound-only or highly sensitive, such as government, financial institution, healthcare, or other enterprise numbers that bad actors may try to spoof.

The purpose is to reduce caller ID spoofing. If someone tries to originate a call while presenting a DNO-protected number as the source, the carrier can block or reject the call before it reaches the recipient.

How this can affect Pylon Phone routing

In Pylon Phone, an inbound caller may successfully reach your Pylon phone number and create a phone issue. However, when Pylon routes that call to agents, a separate outbound leg may be created from the call to each agent. If the carrier rejects that outbound leg because the original caller’s number is on a DNO list, the agent may never ring.

What support teams may see

A common sign is that the inbound call issue exists, but there is no normal routing audit event showing agents were rung. In Pylon, that may look like:

• The phone issue is created successfully.

• The call flow or trigger appears to have started.

• There is no Inbound Call Ringing Agents audit event on the issue.

• The caller may hear ringing or silence briefly, then the call ends or falls back according to the call flow.

Behind the scenes, the routing attempt may have failed before Pylon could record the normal “ringing agents” audit log.

How to think about the issue

DNO behavior is source-number deterministic. The same Pylon phone number, call flow, trigger, and agents may work for one caller number but fail for another caller number if the failing caller number is protected by a DNO list.

If a normal mobile or local number routes to agents correctly, but a bank, card issuer, government, or other protected toll-free number does not, the DNO list is a likely explanation.

What to do next

• Confirm whether the failed calls are consistently from the same caller number.

• Compare against a successful test call from a non-protected number using the same Pylon phone number and call flow.

• If support confirms a DNO-style carrier rejection, contact Pylon Support with the affected call issue, caller number, destination Pylon number, and timestamp.

Pylon Support can review the call routing logs and confirm whether the carrier rejected the outbound agent leg because of DNO restrictions.