German iPhone 5S in America LTE

Dear fellow people,

I'm from Germany and studying in the US and I got my iPhone 5S in Germany. Now I was able to use LTE back in Germany but when I come to the US and got a Tmobile number I only get 4G.

Which is not bad but I want to get full LTE just like the iPhone 5S should be supporting.

I even tried to add the line of code front Tmobile to enable LTE in the phones settings but nothing happened.

Is there anything I can do or what I need to make it happen?

Unless that German iPhone supports the US T-Mobile LTE frequencies (1700/2100 MHz AWS so as you can see it doesn't), you won't be using it on LTE.

LTE Frequencies in Germany

Unlike American carriers, German operators can use the 800 MHz, 1,800 MHz and 2,600 MHz frequencies for LTE. Right now, Vodafone and O2 are just using the 800 MHz frequency for LTE in Germany, Vodafone even in Dusseldorf and in the near future in other cities. That is why they offer download speeds of just up to 50 mbps. So far, Telekom is the only provider using the 1,800 MHZ frequency in Cologne and Frankfort which allows for higher download speeds of up to 100 mbps. The 2,600 MHz will be employed as soon as more customers use LTE services and the carriers have to provide more capacity on their 4G networks.

You will only get 4G where the cells on the network have been upgraded. It may well be that 4G is not available in the specific cells you use.

My personal experience is that 4G is very finicky, so here in the UK I can often end up with a 3G(H++) signal even when I can see a cell tower that has been upgraded!