Obihai was just purchased by Polycom. They are offering a sale on this same device in this thread, for the same $35.
https://www.newegg.com/Product/Produ...08&ignorebbr=1
Get the OBi200 for Only $34.99 Now Thru Thursday, April 12th *
Newegg Promo Code: EMCPTER78
TL;DR: If you have an internet connection, this gadget allows you to hook up any normal phone equipment, including cordless sets, and make/receive free calls via Google Voice. One $35 charge up front for the box, then no service or any other required fees (small caveats in the thread above if you want E911 service).