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Telstra to (actually) implement SPAM call blocking

Update: If you need to use a number that is owned by Telstra, you can request we whitelist the number in Telstra’s systems here.

Around 18 months ago we wrote about changes Telstra was proposing to help combat SPAM calls. The original proposed changes were later shelved due to challenges in their proposed implementation.

Telstra has confirmed they intend to proceed with this program from the 2nd March 2023. These changes will affect calls where the Caller ID is owned by Telstra, but the call is traversing through another network, and later returning to Telstra. This may impact you when calls are being made during a number porting process (for instance, migrating your numbers to Real World), or where you have a multi-carrier environment and the number you use for outbound calls is with Telstra.

From the 2nd of March 2023 Telstra plans to implement restrictions on calls received at their domestic Points of Interconnect (POI) with Telstra caller-ID. Calls will be answered with an IVR rather than blocking, as previously foreshadowed. The caller will be asked to press a nominated digit to proceed. If the correct number is received the call will proceed, otherwise the call will be blocked.

As before, our recommended course of action is to port your numbers that are currently with Telstra to us to avoid this treatment.

We remain committed to working with our carriers, Telstra, and the wider industry to reduce SCAM calls and reduce the impact on consumers. We understand that the below design will be inconvenient for some of our customers, and we are not convinced that it will achieve the purpose it sets out to achieve.

We have pulled together a brief FAQ below to address potential questions you may have, which we will continue to build upon over the next few weeks.


Can we view a copy of the IVR transcript?

The call will be answered by an IVR, and the caller will be asked to enter a random digit greeted by the message “To connect your call, press X.”

If the caller does not respond, or enters the wrong digit, the process will start again, “To connect your call, press Y.”

If the caller does not respond or enters the wrong digit for the second time, the process will start again “To connect your call, press Z.”

If the caller does not respond or enters the wrong digit for the third time, the call will be disconnected.

The caller has 3 seconds to provide a response at each attempt. If a correct response is provided, the call will proceed.

SIP blocking codes

Where calls are answered by IVR and a correct response is not received in the time allowed, the call will be ended from the Telstra side with:
SIP “BYE” message on SIP, or
ISUP  “RELEASE” message on TDM

Will calls to emergency services be impacted

No. Calls to emergency services (000) will never go to the Telstra IVR. 

How will IVR affect customers who are abroad using mobile roaming?

Telstra have advised that IVR will not affect Telstra mobile customers roaming abroad.

Will calls that originate from the Telstra Network using Telstra CLIs be subject to IVR?

Telstra have indicated that calls originating with Telstra CLIs on the Telstra network and handed over to any other carrier, then returned to the Telstra Network at a domestic POI with the same CLIs within a prescribed period (currently 2 hours), will not be subject to the IVR.

The 2-hour timeframe seems short, are we able to receive a longer window?

Telstra have advised the timing window is 2 hours, we have asked for an extension on the window and will revert on their decision as soon as we know more.

Are we able to whitelist numbers with Telstra for legitimate use cases to avoid the IVR?

Telstra has advised that it will be possible to whitelist Telstra held CLIs where CSPs are using Telstra held CLIs with the consent of the rights of use holder. Calls from a whitelisted CLI will not be sent via the IVR.

We are clarifying the process for whitelisting of CLI and will send further detail on this soon.

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