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What is “SMS Scam Filter” and how does it work?

Telstra has rolled out scam SMS blocking technology across their mobile network. Since Belong use parts of the Telstra mobile network, this technology will also apply to people using our mobile plans.

Here’s what you need to know.

How does SMS Scam Filter work?

This new capability is designed to find and block SMS scam messages with suspicious links as they travel across our network, stopping them before they reach our customers’ mobile phones. It’s another tool in the fight against SMS scams and extends Telstra’s industry-leading where we have already protected our customers by blocking over 100 million scam calls in the past year.

This capability is complex but in simple terms it applies knowledge of what a scam SMS looks like as it travels across our network and if it looks suspicious it will block the SMS for customers. It does this by automatically machine scanning the content of messages travelling on our network to find suspicious patterns and characteristics, along with other data including time, sender, number of messages sent, and recipient.

To avoid blocking something legitimate, the new message format may be reviewed by our specialists to identify if the message is a scam, but the details of the recipients will remain masked.

Suspicious SMS are reviewed to identify if the message is a scam (the details of recipient remain masked). If a scam is identified, the technology will block future messages with the same criteria or near matches.

The capability does not offer a fool-proof solution to scams; criminals evolve and find new methods to attempt to scam Australians. For example, if they suspect we have blocked message that has a suspicious link, they will try to change the characteristics in the SMS to avoid being blocked.

We must continue to be alert to the possibility that when we receive an unexpected message, that it may not be genuine and not click on links.

Will it block a message that I wanted to receive?

We can’t guarantee 100% accuracy of the scam filter so there is a very small chance that a legitimate message won’t be delivered. Telstra haven’t received any substantiated complaints about this happening since their pilot for SMS blocking started in 2021.

Could high-volume messages be mistaken for scams?

Legitimate commercial messaging sources on Telstra's network are excluded from blocking. This means that SMS sent by banks and other businesses, government departments, Emergency Alerts, and Telstra applications like MessageBank aren’t scanned and won’t be blocked.

Some scammers use our handset plans to send high volumes of traffic in breach of our Acceptable Use Policy. Messages sent from a service on a mobile plan will be scanned and may be considered potential scam.

If a Business sending many legitimate messages has evidence that they are not being delivered, they should report a fault as normal. Our fault teams are equipped to assist.

Did we build it ourselves or use an off the shelf product?

The product used for this technology is provided by one of Telstra’s specialist telecommunications suppliers. It is operated by Telstra staff in Australia.

How can I opt out of scam SMS blocking?

When activated, the SMS scam filter will block thousands of malicious SMS messages sent to Belong customers. Most customers will enjoy the benefit and not wish to opt out.

At launch, all Belong customers will have this technology turned on throughout the mobile network. To opt-out, send an SMS to 0438214682 with the words FILTER OFF.

How will I know if the opt-out or opt-in has worked properly?

When you send an SMS to 0438214682 you will receive an automated response as follows:

Text message to respond to FILTER ON from customer

The SMS Scam Filter is now activated for your mobile service. This technology is designed to reduce the number of SMS Scam messages delivered to your mobile service.  You can optout of this service by texting FILTER OFF to 0438214682.

Text message to respond to FILTER OFF from customer

The SMS Scam Filter is now OFF for this service. To turn on, text FILTER ON to 0438214682.

Text to respond to FILTER STATUS (whichever is appropriate)

The SMS Scam Filter is now OFF for this service. To turn on, text FILTER ON to 0438214682.

The SMS Scam Filter is now ON for this mobile service. This technology is designed to reduce the number of SMS Scam messages delivered to your mobile service. You can opt out of this service by texting FILTER OFF to 0438214682.

Text to respond to any other input

Sorry, the command you sent was unrecognised. Please send a message that contains one of the following commands:
FILTER ON - opt in for the Scam Filter
FILTER OFF - opt out of the Scam Filter
FILTER STATUS - display current applied status of the Scam Filter

It won’t stop all scam messages, right? If so, how can customers report scams that slip through?

Unsolicited or unwanted commercial messages ("spam") will not be blocked by the scam filter. Legitimate businesses are obliged to let you stop their marketing, typically by replying STOP. This filter is designed to block SMS aiming to trick you into clicking on a malicious link.

The commercial blocking platform has a demonstrated history of accurately blocking scam messages for other mobile operators. Messages will only be blocked if verified to be part of a scam campaign, against agreed criteria and with support from our cyber and scam experts.

If you receive a message that you believe is a scam, please let us know by contacting us at

What human intervention is used, or is it all AI?

The technology requires some degree of manual review.  A small team reviews a sample of suspected scam messages including the hyperlink.

The recipient data are removed to protect privacy before the suspicious content is manually reviewed. If the team identifies a message as scam, the technology will block future messages with the same criteria or near matches unless the recipient has opted out.   This manual confirmation helps reduce the risk that legitimate messages are blocked. The platform is also set up so it cannot be used for any other purpose. It is secured to the same high standard as the rest of our network, with access restricted and logged. 

I'm concerned about my privacy, what else is Belong monitoring in the background under the guise of "security"?

We take our obligations very seriously and we operate in accordance with all legislation.

The SMS scam filter system is designed and operated exclusively for blocking scam messages. It cannot be used to monitor any individual or conversation topics.

Access to the platform is restricted to specialist Telstra staff in Australia who will review an anonymised sample of a suspected scam message to verify whether it is part of a scam or cybercrime campaign without viewing recipient identity. All access is strictly restricted, logged, and monitored. Access is reviewed on a regular basis. 

The platform has undergone security penetration testing to ensure it is not accessible to external or internal hacking and abuse. It is built and maintained according to cyber security best practices, as we remain committed to maintaining the privacy of our customers.

Can this system be applied to other messaging apps like WhatsApp, or is it just SMS?

The SMS scam filter can only be applied to SMS on services on the Belong mobile network. It will not be applied for "over the top" messaging applications like iMessage, WhatsApp, Facebook Messenger, or end-to-end encrypted services.

If you receive a scam using one of those applications, you should report it to the operator of the service.

Will you be blocking unsolicited political messages? 

Politicians, charities, and religious organisations are some of the organisations and entities that have exemptions to the Spam Act. They will not be blocked under this platform.

Will my SMS messages and related metadata stay in Australia? 

Yes. Your communications including SMS and attached metadata will remain located in Australia on Telstra infrastructure. Nothing has changed. Our privacy statement will also apply to your involvement. for more information.

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