I've been having data connectivity issues since June/July. I thought it was a software update or maybe a glitch. I tried the ##7... option, no luck. I did a factory reset on my phone last week, still nothing. I try turning the data off and on, turning the phone off an on, no fix. On occasion, I'll get a minute or two of data connectivity but no more unless I can get on wifi. I'll have everything from full bars on LTE to mostly full bars on 3G to roaming at the same location in the same day. Sometimes the exclamation point shows up on the signal bar icon, sometimes it doesn't. This happens whether I'm at home, at work, visiting out of town, or on the road. My spouse has a different phone, same service, and has no problems. It's definitely with the phone. I've had the phone for just over a year and it looks like I'll need to replace it. Might replace services too, it's not worth paying $35-$45/month to only be able to make phone calls and otherwise it's a brick unless it's on wifi.
