yes just had this problem yesterday, go into settings go into advanced calling and activate or hit the advanced HD calling feature and that should take care of it switching to the one x, trust me I was on phone with tech support with the same problem. and I haven't had a problem since also the advanced calling feature is free I just think you might have to call in to have it activated on there end too. but try that first then turn your phone off, leave it off for about 45 seconds and turn it back on and it should work fine. let me know how it goes.
I was about to changemail my phone when the guy at the store enabled the advanced calling feature and everything worked as it should. As for weak Bluetooth, he said wait for the system update and that should be fixed as well. Other than the iPhone type design of this phone I'm liking the speed of it and many features.