On City of Valdosta sewer, the line running from your house out toward the City's main is yours. The City's own sewer page says stoppages from roots and grease happen in “the external drain lines owned by the property owner,” and asks property owners to call a plumbing repair service first.
If the plumber traces the problem into the City's sewer lines, the City says the plumber should contact City of Valdosta Utilities, and a crew is sent to check them. A sewer smell outside the building is also reported to that number.
. Sewage overflowing from a manhole after hours? See who to call in a plumbing emergency.