The easiest way to check your balance, is by signing into My O2, online or through the app.

Otherwise, you can try one of the following:

• Press Hotkey 2 on your mobile phone
• Key *#10# then press the call button
• Dial 4444 for free from your mobile

Remember: you need at least one minute of calltime credit to make a call. When your calltime falls below this point, you'll receive messages reminding you that you are nearly out of credit. Eventually, you will be diverted to the O2 Top-Up Line.

Checking your balance from a different phone

You can sign in to My O2 from any device to check your balance, even if you don’t have your sim with you. You’ll need to be registered with My O2 to do this.

Not registered with My O2? Here’s how to check your balance:

• Pop your sim into a phone
• Turn wifi off, so that you’re connected to our data network
• Go to My O2, where you can check your balance without signing in. Don’t worry – you won’t be charged for using data on the My O2 website

If you're not sure about any techy terms, check out our jargon buster.