Is my iPhone 7 Plus 3G or 4G?

I just heard phones that are only 3G compatible will be obsolete in the next few months….worthless basically. If true, is there a way to see if my iPhone 7 Plus is 3G or 4G? And without signing up for a “free” service that wants your credit card info? I found a site that claims for free you enter your IMEI # and the report generated tells you. But when they wanted a credit card, I closed it out. Thanks for any help with this!