Port-forwarding a landline question

I was going to try to port-forward my Xfinity landline to an Xfinity mobile number in a bid to get my elderly mother to use a smartphone. She's had the landline number forever and does not want another one. This is probably a dumb question, but if I port-forward a landline.......does the land line still work? My family and I want her to have a cell phone for emergencies, but I'd still like her to have access to the working land line as well.

Thanks.