Hitmaker Alex Da Kid tweeted that T.I.'s "Castle Walls" was serviced to radio earlier today. This means it'll be the third official single from the incarcerated rapper's No Mercy album. We're not sure if T.I. will be shooting a visual for the single since, well, he's in jail, but there is a possibility that he shot a video with Christina Aguilera (who's featured on the song) before his sentencing. On a lighter note, No Mercy just went gold, which is great. "Castle Walls" sounds like it has potential as a single, and both of these artists could use a hit.

T.I. f/ Christina Aguilera "Castle Walls"

[via ThatGrapeJuice]

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