Call on GV 8 (iOS 8) cydia tweak is a Cydia substrate extension to integrate calling via Google Voice into native Phone app. The extension also works when calls are made from outside the Phone app (for example, from a website). It may not work with other Cydia extensions like Call Bar.
Call on GV supports:
Three calling mechanisms (in addition to the default carrier calling):
This tweak is tested and supported on multiple versions of iPhones (only the callback calling method can be used without a cell service).
It is likely not to work on iPods and iPads (as it modifies the Mobile Phone app) and hence not supported.
Call on GV requires a RESPRING after installation or update. So, respring your device before you do anything.