new sim card from AT&T doesn't work in my iphone

Hello. I had been having issues with my iphone SE for a few days. I talked to the online chat agent and they decided it was a SIM card issue so they sent me a new one right away. I replaced the SIM card in my phone. The wifi connection seems to be fine, but it says No Service in the left corner and I cannot make any calls an ACT107 error (ACT107: Looks like there aren't any numbers eligible for activation on the associated account.). The error message gives me a phone number to call. However, I can't make any phone calls because my phone doesn't work. And I cannot find the online chat option anywhere on the ATT website. There are zero online contact options except for this forum. So I'm stuck. Any advice is appreciated. Thank you!