It's common for iPhone users to have their privacy settings set as to deny any access to the microphone, camera and location in Safari. In that case, there is a prompt to change those settings, but if that's not clear enough, here is how you can instruct your customers to enable access:
1. Go to "Settings", and scroll down and click on Safari:
2. Scroll down to the bottom:
3. Select Camera and Allow:
4. Select Microphone and Allow:
5. Select Location and Allow:
6. Go back to Home screen and go to "Settings", and scroll down and click on Privacy:
7. Select Location Services:
8. Select Safari Websites:
9. Select either "Ask Next Time" or "While Using the App":
Finally, return back to the link that was sent to connect to the Visual Support session