More than likely, the model you have does not support the LTE bands being used by your carrier.

See this list: http://www.apple.com/iphone/LTE/

So are you using T-Mobile USA?

So, it sounds like you should contact Ting and ask why you can't access the Sprint LTE network with your phone.

As LACAllen said you need to discuss this with Ting. It may be a problem with the nanoSIM you got from them or it could be the carrier settings on your phone. While Ting is an MVNO using the T-Mobile network are they an approved iPhone provider?

And I believe LACAllen meant the T-Mobile LTE network.

Yes I did. Thanks for catching that.

The ability to have particular settings on your device is determined by the carrier file. Depending on the carrier file that is located on your device, evidenced by the listing under Settings>General>About>Carrier, that determines what switches you will find in specific areas of the phone. I would ask your carrier what carrier file version you should have on your device to have the settings for LTE.

As far as the issues with iOS updates, if you come here or to many other forums, you find people that are complaining, not ones that are gushing about wonderful things that occur with updates. This forum will also show you threads after each iOS update claiming it is the worse, it is the one that ruined my device, and what was Apple thinking. Intelligent use and update of devices will keep things in perspective. You will also see that 99% of the problems encountered during an update are device specific. Not model specific, but individual user device specific, where a user has done something or has some content that has caused an issue with the update. A restore to factory usually corrects these issues, but requires the user to sync content back individually, not from a backup, as that backup can contain the problematic file/date and just moves it right back to the device.

You need to contact Ting again to determine what carrier file you need to be using. They should be able to tell you, especially if it is theirs, or one from T-Mobile.

Here's the T-Mobile bands:

LTE Frequencies:

1700 MHz & 2100 MHz AWS band 4

1900 MHz PCS band 2 (in refarmed areas)

Lower 700 MHz band 12 (in development) / in service in selected areas

 

3G/4G Frequencies (WCDMA):

1700 MHz & 2100 MHz AWS band 4

1900 MHz PCS band 2 (in refarmed areas)

 

2G Frequencies (GSM/GPRS/EDGE):

1900 MHz PCS band 2

You're welcome.