$39.99 at Newegg with Promo Code: EMCTEUT56 until 11:59PM PT on 09/12/2019.

This is as good as the price gets these days.

This is an Analog Telephone Adapter. You plug it in your broadband Internet and an analog telephone (or cordless phone base). Functionally it works in the same way as cable telephone, Ooma, Magic Jack, Vonage, except the service is free with Google Voice. There is no usage cost and no monthly or other recurring costs. IIRC, free calls to/from Canada too.

Google Voice does not handle 911 calls. You can add 911 from Callcentric (and others). Callcentric 911 is $1.50 a month, plus a $5 deposit.

It can also be used with other SIP phone service providers like Callcentric, but those are not free.

I have been using one for years as my home phone. It works great most of the time as long as electric and Internet are up.