I know nothing about this.
Get a Google Voice phone number. Think it's free. See Android, iOS, and Web options. Thinking Web would be correct option because I Have no phone at this point.
Buy this:
OBi300
Poly OBi300 VoIP adapter offers the flexibility to use an analog telephone through a Bluetooth device. It supports an optional Wifi Accessory to expand range.
www.poly.com
Buy this:
WiFi Adapter
USB Wi-Fi accessory for VoIP adapters
www.poly.com

Use a old corded house phone. Or buy a new cool looking
PINK one.

Not finding any written good set up instructions. Here is a video.
How to Set-up Google Voice on Your OBi - New
I don't do well with watching videos. Here is transcript:
how to configure Google Voice with the
OB this tutorial will show you how to
setup your OB device and configure it
with Google Voice you will need a phone
router with internet access Ethernet
cable you'll be device and the Obie's
power adapter step 1 connect the power
adapter to the Oki
step to connect your phone to the obese
phone port
step 3 connect one end of the ethernet
cable to the routers land port
step four connect the other end of the
ethernet cable to the Obi's Internet
pick up the phone connected to the Obi
and dial star star 9 followed by nine
twos to perform the echo test next go to
Obito comm and sign up your new Obi talk
account the easiest way is to sign up
for Obi talk by selecting sign in Google
if you wish to use a non gmail email
simply select create a new account when
you first log in Obi talk you'll be
prompted to add your device click yes to
add your device Tobey Tom when you're
ready select next and dial star star 5
plus the number on your screen once you
have read through the Google Terms of
Service select accept and continue with
your Google Voice setup for seven digit
dialing into your local area code here a
Google window will appear where you will
be prompted to select accept to allow
there will be permission to use Google
for calls please allow approximately two
minutes for Google Voice to be
configured on your device the status
will show configuring Google Voice
status will show connected once setup is
complete
I don't do well with no sentences, periods and capitals. Will try top fix all this.
How to configure Google Voice with the OB this tutorial will show you how to setup your OB device and configure it with Google Voice. You will need a phone router with internet access Ethernet cable you'll be device and the Obie's power adapter.
Step 1 connect the power adapter to the Oki
Step 2 connect your phone to the obese phone port
Step 3 connect one end of the ethernet cable to the routers land port
Step 4 connect the other end of the ethernet cable to the Obi's Internet
Pick up the phone connected to the Obi and dial star star 9 followed by nine twos to perform the echo test. Next go to Obito comm and sign up your new Obi talk account the easiest way is to sign up for Obi talk by selecting sign in Google. If you wish to use a non gmail email simply select create a new account when you first log in Obi talk you'll be prompted to add your device click yes to add your device Tobey Tom when you're ready select next and dial star star 5 plus the number on your screen. Once you have read through the Google Terms of Service select accept and continue with your Google Voice setup for seven digit dialing into your local area code here a Google window will appear where you will be prompted to select accept to allow. There will be permission to use Google for calls. Please allow approximately two minutes for Google Voice to be configured on your device. The status will show configuring Google Voice status will show connected once setup is complete.
Sorry about the poor transcript translation.
Link to - Polycom OBi300 Installation and Configuration Guide.
Hope this all works? Any better options for a free house phone?