Unable to upgrade to new gateway; no cell service here. What to do?

I live 8 miles outside of downtown Seattle but the immediate area gets 1 bar... on a good day. Xfinity seems to have brilliantly decided that gateway activation requires their app. But the moment I unplug my existing gateway I am offline. Period. No phone, no app, no internet, nothing. 

Is there some other way to get this done?