How hard it is to verify if, in fact the seller is truthful when he says it came from the Omni Center in Atlanta,GA?
http://m.ebay.com/itm/Brown-Bell-South-Pay-Phone-Housing-Omni-Phone-/192276303912
?txnId=1424554244009#vi__app-cvip-panel
You probably don't have a provenance, unless there was some special characteristic of it that would place it. I've not seen a brown colored Bell South payphone before.
Looks like it was repainted. Notice the over-spray on the black backboard.
-MM
There was another brown single slot coin phone on EBay a while back. Seller said it came from the Georgia World Congress Center in Atlanta.