To set up Vodafone Visual Voicemail on your iPhone, ensure you have the latest iOS version. Then, open the Phone app, tap Voicemail, and follow the prompts to set up your voicemail password and greeting. Ensure your iPhone is connected to the Vodafone network. If Visual Voicemail isn't activated, contact Vodafone customer service for assistance. You may also need to reset network settings: go to Settings > General > Reset > Reset Network Settings. If issues persist, restarting your iPhone or reinserting your SIM card might help.