If you are renting a modem from your Internet Service Provider/ISP (Comcast, Astound, Cox, etc.), then having your own modem should reduce your monthly bill.
Wired modem only. Doesn't include WiFi Router or VOIP Telephone adapter.
When new this cable modem costs around $175 on Amazon.
It comes with an A/C power adapter and a short BNC Coaxial Cable.
https://www.netgear.com/home/wifi/modems/cm1100/
Not compatible with Verizon, AT&T, CenturyLink, DSL providers, DirecTV, DISH and any bundled voice service.