XA2 works for calls, but Xperia 10 II doesn't

Both use Suomenlinna My provider is H2O Wireless ran on ATT lines in the US. My Xperia 10 II just fails the call, no network found. But my XA2 works just fine. Anyone have any ideas as to why?

Looks like the only differences in 3G bands are Xperia 10 II uses 1700(AWS) band, but XA2 uses 1900. Not sure if that has anything to do with it?

You should be able to tell with CellMon | OpenRepos.net — Community Repository System
If the XA2 is only ever on bands not supported by the 10 II, then yes.

Tried to check it on there, it doesn’t show the band.

Surely frequency to frequency-band conversion is a googlable thing…

Edit: CellMon shows both band number and frequency for me…