New phone service, some calls being forwarded to my cell

I just transferred to XFinity Voice, Internet and TV from AT&T. When I signed up for XFinity, they sent me through a process to have my phone number ported over from AT&T. After the installation, I called AT&T to cancel all phone, tv and internet service. When a call comes through from a phone with AT&T service the call is automatically being forwarded to my cell phone which is still with AT&T. Any other calls coming in from phones with other providers (non-ATT) are coming through on my home phone just fine.  Does this sound like an issue with the porting of the number or an installation issue? I've called support and have a ticket created by haven't heard back from them yet.