Why would they say it may not work on 4G LTE in the U.S.?
Caterpillar CAT S41 - 
United States of America, T-Mobile
Sub-Model
2G
3G
4G LTE
Europe
1900MHz
1900MHz
Band2-1900MHz
Americas
1900MHz
AWS, 1900MHz
Band12-700MHz, Band4-AWS, Band2-1900MHz
Asia Pacific, Latin America
1900MHz
AWS, 1900MHz
Band4-AWS, Band2-1900MHz