Who is your current wireless carrier? this matters as well.
ATT has WiFi Calling. This means if you have wifi you can use your phone as if you are in the US. I have ATT and my phone works with calling/texting like I'm in the US.
Tmobile offers free international roaming with most of their plans.
I'm not 100% on the other carriers but I think Sprint also has Wifi calling.
This means you can buy/rent a mobile wifi puck and use your phone if so.