I know it's annoying but the best solution here just seems to change your number. Don't lose your mind over this one.
edit : seems like people don't understand my post. If you have a voice, the good thing to do is to make a blog post and submit it to websites like HN. The guy did it, now what can he do if he needs a quick fix? If he's in rush? Change number. It's really not that terrible and I do it every year without trouble.
Yes, asking everyone to use a new number is less work than asking people to delete all their imessage threads. Updating contact info at work and with services shifts the burden to him.
I don't get if your comment is sarcastic or not. If it is, I don't see why it would be such a huge problem. It's a quickfix and if I were him, and in a rush to fix the problem, I would do that. I'm personally changing my phone number every year and it's never been a burden.
It wasn't sarcastic I was agreeing with you. I guess other people thought I was being sarcastic too because you got downvoted and I didn't. I don't know, seems kind of obvious. I use google voice, I never have to change my number when switching phones. I don't know how that would impact imessage. I wouldn't ever use such a service baked into the phone by the phone maker.
While one might lose their email losing a phone number is way way harder.
I'm not sure how it works in US but in Finland you have guaranteed transferring across operators. Guaranteed as in fines will tick if the operator from which the number is transferred away is having some 'problems'. Not surprisingly those kind of problems are almost nonexistent.
if he doesn't have the same friends it's not a problem. I mean, he wrote that blog post, posted on HN and on various websites. It's getting attention. It's good. Now the guy still has to fix it so he can still contact his friends.
edit : seems like people don't understand my post. If you have a voice, the good thing to do is to make a blog post and submit it to websites like HN. The guy did it, now what can he do if he needs a quick fix? If he's in rush? Change number. It's really not that terrible and I do it every year without trouble.