GVJack Alternative

The GVJack / GVMate is nothing more than a cloned MJ dongle, working as a USB audio adapter.  It has no built-in processing hardware like a OBi or any other ATA product.  All it does is make an analog telephone work like a USB-attached headset, with a Touch Tone keypad added.  This is exactly how the original MagicJack worked:  all the dongle did was interface with MJ's Windows software.  PCPhoneSoft's advertising is misleading, to say the least.  You'll notice they do more bragging than actual disclosure of how things work.

You still need to run their MS Windows software, which is not doing anything remarkable or special to "hack" into Google Voice, other than acting as you would yourself, placing a call on a computer's web browser with Google's own Hangouts system.  Now, whether or not they are honestly using XMPP, WebRTC with HTML5, or whatever, to do that, or just doing some sort of force-feeding keystrokes into the actual Hangouts app, is unknown.  You won't be able to use a Raspberry Pi or any other low-cost Linux processor, since their product requires their Windows application to work.

There have been years of discussion on the web of similar solutions using MJ dongles plugged into old, cheap "thin client" PCs running Windows XP Embedded, to create a kludge of an ATA.  There are guys selling this bundle on eBay.  Keep in mind that those thin clients are hopelessly outdated by now, and you can't just load any Windows software of your choice on them...they were designed for use with server-based Windows, via Citrix, for example.  If you do want to create a "GVJack" solution, a cheap/used/eBay special laptop would be the way to go, until the processor fan clogs up with dirt or otherwise dies and the thing fries, and you'd have to constantly futz with keeping the software updated.  If this turns you on, then happy hacking!