If you are having issues with visual voicemail not working on iPhone then here’s a few tips on how to get it working! It’s happened to me a few times whether it’s because I switched phones, changed plans or got a new sim.

1. Contact o2 customer support. You can do this from your o2 phone by dialling 202, or contact them on social media at facebook, twitter or instagram and drop them a message.
2. Ask them to turn on the “iData Bolt On”
3. On your iPhone go to Settings > General > Transfer or Rest iPhone > Reset > Reset Network Settings

After you’ve done step 3 your phone should reboot and hopefully visual voicemail will start working.