What are the requirements? TEL3 Support Team Updated November 15, 2016 23:14 Follow Compatible with iOS 3.2 and higher An active account Your iPhone number registered as an Instant Access Number Related articles Why do I get an invalid number message when I try to place a call? How can I register my iPhone’s number? Do I need to prepay in order to use the service? Comments 0 comments Article is closed for comments.