We already have 600mhz (band 71), but a TMobile rep told me the manufacturer would develop an update to make the standard non 5g model capable of using the new network.
The S10 supports 600mhz for 4g as well. The specs are on gsmarena. I live in Denver and I noticed a dramatic signal improvement about a month ago which would indicate T-Mobile has lit 600 up for 4g and 5g.
