Yes. The router prioritizes wifi calling above other uses. Anyone on any carrier network can use the router for wifi calling. Most any router can be used for wifi calling, but this one just has the ports and settings already set up to prioritize.
Welcome, Steve! This is a bit of a tricky question - though the router is designed to prioritize T-Mobile Wi-Fi calls over other activity, typically, since unlocked equipment doesn't have T-Mobile's carrier software, Wi-Fi calling isn't something we can guarantee will work once you're using T-Mobile. Have your SIMs come in yet?
I have a Galaxy S6, Verizon branded and can't even turn on wifi calling. I called support today and was told that wifi calling ONLY works with T-mobile branded phones which is bizarre, my husband has an unbranded iphone and it works but they told me that even an unbranded android won't have an option for wifi. Coverage is spotty and I'm not sure I can stay with T-mobile without wifi calling.