LTE or 4G is a standard for wireless communication of high-speed data for mobile phones and data terminals. The processor on the Jolla Phone supports 4G LTE but you cannot enable it. According to Jukka Heikkilä you can do it using the Terminal App
If you don’t know how to it, there’s an app for that! 4G/3G Radio Switcher allows you to enable 4G Connection on your phone.
This app creates two desktop icons with functionality to toggle between 2G/3G radio 4G/LTE radio.
•3G Switch icon toggles the 2G/3G radio on
•4G Switch icon toggles the 4G/LTE radio on
With current software 4G/LTE power consumption is significant and circuit switched fallback (CSFB) does not work. This means that LTE can be used with power supply connected and you will not receive phone calls or SMS while LTE is on.
Download it here or scan the image below