The 'Dead And Gone' star, real name Clifford Harris, pleaded guilty to the charges last March after being arrested in 2007 for attempting to buy unregistered machine guns and silencers.
According to The AP, the rapper had faced a maximum of ten years in prison and a $250,000 fine per charge until he negotiated a plea deal last year.
He has already completed around 1,000 hours of community service, but will need to complete a further 470 under the terms of the deal.
T.I., 28, previously claimed that he had wanted the guns out of fear for his safety after a friend was murdered in 2006.
He has been given between 30 and 60 days to report to prison to begin his sentence, although an attorney for the star has admitted that it is not certain where he will serve it.