first smartphone, confused about cross-carrier compatibility

I'm a long-time T-mobile customer, still using a flip phone. I finally decided to join the modern world and get an Android smartphone. Not surprisingly, I got bogged down researching phones -- so much to learn, so little time!

My sister offered to give me her retired Galaxy S5 so I can get my feet wet. That will allow me to get a feel for what's important to me before dropping some big bucks on a current-gen flagship phone. Her provider is US Cellular so she would need to ask her dealer if they would be willing to unlock the phone and then mail the phone to me cross-country.

Before I ask her to do that, I want to make sure her phone will work on T-Mobile's GSM network. According to the S5 Wikipedida page, the model sold by US Cellular (G900R4) supports GSM but beyond that, there are lots of differences in the bands that I don't understand.

Once unlocked, can I use her S5 on T-Mobile?

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No one??

I haven't tested myself, however, according to Samsung's official page for this specific model number (SM-G900R) sold by USC, this particular model number does NOT have GSM support of any kind.

Check the link here and scroll down to Networks: https://www.samsung.com/us/mobile/ce...0RZKAUSC-specs

There, you will see: LTE: Bands 2/4/5/12/17; CDMA 1x/EVDO Rev.A: 800/1900MHz

Technically, it seems to have compatibility with T-Mobile's 1900 band, but, because it doesn't seem to have GSM compatibility, the device will most likely NOT work with TMO even if it has been unlocked.

Again, I haven't tested this myself but hopefully the info helps.

Thanks for that link. I wasn't aware Samsung had carrier specific specs. The Wikipedia page must have it wrong... although it seems to have a lot more detail on the radio. In any case, it's not worth the hassle to test it so I told my sister 'no thanks' and moved on. Now I'm looking at the LG G5, which I can buy NIB on eBay for under $200. I like the fact that it has a replaceable battery.

i get just as confused, thank you for clearly some of this up.