The latest internet rumours are suggesting that Apple has approved the Google Voice application for the iPhone.

Originally when Google submitted the application for approval it was rejected by Apple with the reason given that it "duplicated functionality of Apple's own applications". 

The rejection consequently led to an FCC investigation,  which resulted in Apple saying they had not  rejected the application and continued to study it.

Since then Apple has released new guidelines for developers and Google Voice App doesn't seem to breach any of them, which is why it's rumoured to be getting approved shortly.

Google Voice is an application that enables users to combine multiple telephone numbers into one manageable number. When a person rings any one of the numbers you have it  will come through to your Google Voice Account. For Example , You can combine your landline , business and mobile number into one manageable place.