Here's a quick tutorial of what to do to get Phone GV working.
This is working perfectly on my iPhone 5 running 6.1.2.
Note: The files in Step 1 are allegedly modified to provide support for iPhone 5. Some people in the thread using iPhones other than the 5 were able to get this working without modifying any files at all, apparently. If you're using an iPhone 5, continue but be warned your mileage may vary! If you're not using an iPhone 5, check out what some of the people are saying in this thread:
https://plus.google.com/101000267549201413782/posts/FnPPB1fuSJV
(disclaimer: I do not want to be and will not be responsible for any glitched devices. Theoretically if things go sour you should be able to boot into your phone with MobileSubstrate disabled by pressing the volume+ button during boot to remove the tweak. However I cannot guarantee that and subsequently your jailbreak may be lost if you brick your iPhone installing this tweak. Just sayin'! Good luck! ;P)
1) Download PhoneGVExtension.dylib and PhoneGVExtensionHook.dylib files from here:
http://dl.dropbox.com/u/3497819/gvexts1/PhoneGVExtension.dylib
http://dl.dropbox.com/u/3497819/gvexts1/PhoneGVExtensionHook.dylib
(they are modified versions of Zhi Zheng's originals, work credit goes to Andrew Chilvers)
Before proceeding make sure you have some way of putting files onto your phone. I used SSH via WinSCP. You could use iFunbox, or iFile as well. Just make sure you know how to place files onto your phone before proceeding.
2) Search Cydia for Phone GV, and install it. DO NOT RESPRING WHEN CYDIA ASKS YOU TO. Do not close out of Cydia either, just set your iPhone down for a moment.
3) Open up your PC<->iPhone file transferring program of choice. Navigate to Root\Library\MobileSustrate\Dynamic Libraries. Find PhoneGVExtension.dylib and PhoneGVExtensionHook.dylib and rename them with some other extension. I usually use .bak.
4) Now drag the downloaded dylibs from step 1 into Root\Library\MobileSustrate\Dynamic Libraries. They should either overwrite if you opted to not rename the originals, or should just copy over normally.
5) Now you can respring, and Phone GV will be active. You can configure it in Settings.
It's been running perfectly for me for several hours!
Some additional notes:
- I had to respring after configuring Settings\Phone GV to get it to work.
Good luck!