Landline Phone Replacement?

I am currently paying for PLDT's 1699 plan for fiber internet and landline and I've been looking to have this replaced as I don't use their internet anymore since I have Converge, would like to pay for less and because their reception in my area is pretty weak.

What I'm thinking of is a Smart Postpaid 599 Plan as it's cheap and Smart has a stronger signal in my area, but the problem is I don't really want to use it on a cellphone. What I want is something like PLDT's Landline Plus Postpaid where it looks like you can just plug a sim onto their wireless landline, but I'd like to have something like this for the Smart Postpaid plan instead instead of getting the PLDT Postpaid Plan due to the issues I have stated with them. The reason I want this is cause I prefer to have a device that just does one thing and allows me to just leave it plugged on rather than worry about having to charge it all the time.

My question is, does anyone know of the specific model of phone PLDT's Landline Plus uses, or any other recommendations for a landline phone that utilizes a sim slot?