Apple replaced my iPhone 6+ (jailbroken on iOS 8.4: RIP!) with a 9.2.1 6+ on Sunday. Since then, I noticed HSPA+ calls sound like regular 2G calls. VoLTE is obviously off (and will remain that way due to terrible past experiences). Audio quality is certainly a noticeable downgrade. Is something wrong on my end, or did Apple change something in iOS 9? I've restarted several times. The people on the other end are confirmed in standard LTE and HSPA+ areas. I can't remember the last time calls sounded like this... This definitely didn't start happening until after the Sunday replacement. Update: HD Voice calls work with VoLTE enabled. I think restoring from my 8.4 backup was the culprit. I'll wait for the 9.2.1 (or 9.3, whichever comes first) jailbreak before starting from scratch. Update #2: I updated to 9.3b3, and the same thing happens.