Yes, and now the residential land line is becoming obsolete.
The other day our power went out and I tried to call the electric company. Discovered our phones were out also. I had forgot they all plug into the electric outlets. Then I remembered I wouldn't let my husband throw out our old phones when we got these ones. Searched the boxes in the garage found it and plugged it into the phone line and WALA! it worked.
Before you say get a cell phone, cell phones go out also. Also if in an emergency at home 911 may not be able to find you.