maybe a couple of silly questions but again I'm not the brightest candle in the box especially with the new technology
I am currently with Century Link for both phone & internet (40 MBPS)

I realize we are being somewhat forced to the "cell phone technology" by banking, and several other requirements and plan on making the jump soon.

So the questions are:
I believe there are ways have your cell phone utilize the existing hard wired phones in your house while ditching the landlines cost IE: disconnect the phone service. If I am correct are there any drawbacks to doing so ?
Are their particular companies/adapters etc. that are better than others?

And if one does so, does this affect the internet service (DSL) by the same provider. To my knowledge, my location limits me to using the phone companies hardwired phone lines for internet access.

Several times I have called friends on there cell and they couldn't find it at the time which resulted in my calling their landline.
I don't like the idea of having to carry a phone everywhere I go in the house or shop.
It's a bit harder to misplace 4 or 5 phones LOL
TIA