Three Parental Controls & Adult Content Filter Guide
How to check and manage Three's adult content filter on your child's SIM, and how to set spending controls to avoid unexpected charges.
Overview
Three, like all UK mobile networks, applies an adult content filter that blocks 18-plus websites when a phone is using Three's mobile data. On pay as you go SIMs the filter is usually on by default; on pay monthly contracts it is worth checking, as accounts taken out by an adult may have it switched off. This guide explains how to confirm the filter is active on your child's SIM, what it does and does not cover, and how to use spending controls to prevent bill shock.
How Three's Adult Content Filter Works
Three's filter blocks websites classified as suitable only for adults — such as pornography, gambling and other 18-plus material — whenever the phone is browsing over Three's mobile data. Removing the filter requires proving to Three that the account holder is over 18, which is a deliberate safeguard: a child cannot simply switch it off themselves. On pay as you go the filter is normally active from the start, whilst on a contract in a parent's name it may need to be switched on. The exact menu names change from time to time, so check your account through the Three app or three.com to confirm the current position.
Three's filter blocks 18-plus websites over mobile data and can only be removed with adult age verification — but always confirm it is actually switched on for your child's SIM.
Checking and Managing the Filter
The quickest way to check is through the Three app or by signing in to your account on Three's website, where content or age restriction settings sit alongside your other account options. If you cannot find the setting — Three does reorganise its menus occasionally — contact Three's customer service through the app or website and ask them to confirm the adult content filter is active on your child's number. If your child's SIM is on its own account rather than yours, you will need access to that account to manage it.
Use the Three app or your online account to confirm the filter is on, and ask Three's customer service directly if the setting is hard to find.
What the Filter Does Not Cover
Three's filter only works when the phone is using Three's mobile data. The moment your child connects to Wi-Fi — at home, at school or at a friend's house — Three's filter is out of the picture entirely. It also does not control apps, app-store downloads, in-app purchases or what your child sees inside platforms like YouTube or TikTok. Treat the network filter as one useful layer, and pair it with device-level controls such as Apple Screen Time or Google Family Link, plus filtering on your home router.
The network filter stops at mobile data — it does nothing on Wi-Fi or inside apps, so combine it with device and router controls.
Spending Controls and Premium-Rate Charges
A safe SIM is also one that cannot run up a frightening bill. UK networks must let pay monthly customers set a spend cap that limits charges beyond the monthly allowance, and you can usually ask Three to bar premium-rate calls, texts and charge-to-bill purchases on your child's number. Pay as you go has a natural ceiling — the phone stops working when the credit runs out — which is one reason many parents prefer it for a first phone. Review the caps and bars available on your tariff through the Three app or by asking Three directly.
Set a spend cap and ask Three to bar premium-rate services so your child's phone cannot generate surprise charges.
This is practical educational content to support families. For case-specific concerns about a child's safety, contact the NSPCC helpline on 0808 800 5000 or your local safeguarding team.
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Last reviewed: 2026-08-22