Thank you for reaching out to us through the Xfinity forum and my apologies for the discrepancies in the information you’ve encountered. I can confirm to you that by having Xfinity Internet Essentials you do qualify for Xfinity Mobile service. The quote of $4/month is misleading though.
The $4/month price would cover a device payment plan of one of our more cost effect phones such as the Moto E5 Play or LG K30 which are available for $4.99/month. Currently, those models are out of stock in our website and would require going to a Xfinity store to find out if they have it there. Additionally, you would require a data plan to go along with your service and that starts at $12/month per gig used. Let me know of any other questions you may have that I did not address.