This particular issue has been heard of before. What happens is that the iPhone converts text messages into iMessages and sends them to an Apple ID even if its not in use. The sender gets a delivered flag while the message never reaches the recipient since they’re no longer using the Apple ID. Messages get lost somewhere in between. A new report suggests that Apple may finally have acknowledged the issue.
Adam Pash, a former lead editor at Lifehacker, recently wrote about facing this exact same issue. When he contacted Apple Support he was told that this is a problem that is being faced by many people and that the engineering team is working on it but is apparently “clueless as to how to fix it.” Pash was also told that there are no reliable solutions for this issue right now.
He started facing this issue after shifting from an iPhone to an Android device. Obviously the Apple ID is no longer in use and there’s no official iMessage app for Android. An iPhone would automatically convert texts into iMessages if a contact’s phone number is entered in the iPhone field. This may help users who pay per text save money but it evidently results in missed messages when at Apple ID is no longer in use.
The Apple Support rep advised Pash to ask all of his contacts to remove him as a contact and add him again, but this time adding his number in the Mobile field instead of the iPhone field. This isn’t a practical solution as one can’t possibly call up every single person in their contact list to make this request. Lets see if Apple comes up with a fix soon.