The Librem 5 is an open network phone, not locked to any particular network.

The modem featured in Librem 5 is Gemalto’s PLS8. Two variants are used, PLS8-E and PLS8-US. Here’s the detailed list of bands supported:

StandardFrequencyPLS8-EPLS8-US
GSMGSM 850MHz
EGSM 900MHz
DCS 1800MHz
PCS 1900MHz
WCDMABAND1
BAND2
BAND3
BAND4
BAND5
BAND8
LTE-FDDLTE-FDD B1
LTE-FDD B2
LTE-FDD B3
LTE-FDD B4
LTE-FDD B5
LTE-FDD B7
LTE-FDD B8
LTE-FDD B17
LTE-FDD B20

Using frequencycheck.com, you can find your carrier under your country to see which bands are supported by them. However, keep in mind that not all of these bands may be available in your area.

To find out which LTE bands are available from cell towers in your area, you can look at cellmapper.net. Additionally, if you call your carrier they may tell you which LTE bands are available in your area but they also may not divulge this information.

If you require an LTE band that is not supported by either of the modems, then LTE will not be available to you.