When I used to work for a large mobile network, we would spend ages testing the firmware of new devices. Even giants (at the time) like Nokia would release phones which couldn't dial the emergency services, or put out more than the legal limit of radiation, or were in other ways defective. We'd test, send a report back, wait a few weeks, get a new firmware, test again, repeat until everything worked. It took months.…
Well, the fact that big American mobile operators outright blocked or delayed updates for months did not go unnoticed. Testing is one thing, but in my first hand experience, many carriers used this "testing" as a convenient way to block phone updates without preloaded bloatware preferring their services or apps they were paid to put on the phones.
How were you involved with the update process to know this?