Phillip Jacobson was a Starfleet officer in the 24th century.
In 2353, he was named as a Starfleet Operational Support Services officer on a directory placard in Starbase 32, Maxia sector. His office was located in room #65146. (TNG: "Violations", directory)
In 2374, during the Dominion War, the USS Sarajevo reported Captain Jacobson missing in action, while the USS Cochrane and USS Repulse reported him killed in action. (DS9: "In the Pale Moonlight")
This character was only mentioned in writing.