Starfleet Ensign Anna Jameson was an alias adopted by Seven of Nine when she was recruited for a mission by the Federation timeship USS Relativity and sent to Captain Kathryn Janeway's first day touring the USS Voyager in drydock.
Seven used the name only once, when greeted by Lieutenant Joe Carey in engineering. She told him that her service number was 860790 and that she was attempting to realign the EPS manifolds. She also said she was not a member of Voyager's crew but instead was on assignment at Utopia Planitia. (VOY: "Relativity")