I could have very well used the wrong tag

Bought an iPhone 11 yesterday, popped in the SIM card and it’s connected to a network I’m not with. My data works sometimes but it’s been saying “no internet connection” the past few times I’ve turned on my data. I cant send texts but I can still make phone calls.

Going to look at data in settings it’s all connected to the network I’m not with, what do I do to fix this?