Season Five: Call to Arms

 was released on December 1, 2011, paving the way for Star Trek Online to go free-to-play. Season 5 introduces the long awaited duty officer system as well as a skill revamp and overhaul Special Task Force missions.

Combat

 * Space skills revamp
 * Ground skills revamp (January 5, 2012)
 * Space/ground skill split (January 5, 2012)

New starships

 * The Federation Exeter, Gladius, and Sao Paulo class ships
 * 9 new Klingon ships including the Orion, Nausicaan, and Gorn faction ships.
 * A playable Jem'Hadar Attack Ship

Item Sets

 * Omega Force (space and ground)
 * M.A.C.O. (Federation: space and ground)
 * Honor Guard (Klingon: space and ground)
 * Reman Prototype Space Set (April 19, 2012)

Sector Space

 * Transwarp added for episodes

UI & Systems Updates

 * Dilithium economy and exchange
 * Events Calendar (hourly and monthly)
 * Storyline episode progression
 * Mission Journal upgrade
 * Social map facelift (improved lighting and sounds on Earth Space Dock, Starbase 39-Sierra, Deep Space K-7, Deep Space 9)
 * Facelift of Federation tutorial (separate starting points for each career path etc.)

Graphics update

 * DirectX 10, 11, 11.1 Graphics Support (January 5, 2012)

New missions

 * Duty officer system


 * Special Task Force, , revamp


 * An event system was added:
 * Borg Invasion of Defera
 * Mirror Universe Incursion
 * Starfleet Academy Event / Klingon Academy Event
 * Tour the Universe
 * Crystalline Entity
 * and with bonuses for crafting, lore, collecting data samples and Asteroid Mining.
 * Vault Shuttle Event (April 19, 2012)


 * 2 Year Anniversary Event (February 2-6, 2013)
 * (Federation) or (Klingon Empire)
 * (Federation) or (Klingon Empire)


 * Featured Episode Series: "The 2800":
 * (February 11, 2012)
 * (February 18)
 * (February 25)
 * (March 3)
 * (March 11)


 * New Klingon story mission: (April 5, 2012)


 * First Contact Day (April 5-9, 2012)


 * Introduction of recurring Friday 13th event: (April 12-14, 2012)

Locations

 * Klingon Academy, Qo'noS
 * Q's Winter Wonderland (December 8, 2011 - January 9, 2012)
 * Hathon on Bajor (February 18, 2012)
 * Ayala System (March 3, 2012)
 * Vlugta Asteroid Field (March 11, 2012)
 * Orith System (April 5, 2012)
 * Utopia Planitia Shipyards (April 5-9, 2012)

Free-to-Play Test
The Free-to-Play build was first released on Tribble 29 September 2011. Cryptic held an extended testing period Tribble Test Weekend from 29 September 2011 until 30 November 2011. Players who participated could receive various cumulative rewards, released on 8 December 2011: