A trading turret or dealer board is a specialized telephony key system that is generally used by financial traders on their trading desks. Trading has progressed from floor trading through phone trading to electronic trading during the later half of the twentieth century with phone trading having dominated during the 1980s and 1990s. Although most trading volume is now done via electronic trading platforms, some phone trading persists and trading turrets are common on trading desks of investment banks.
Voice trading turrets
Trading turrets, unlike typical phone systems, have a number of features, functions and capabilities specifically designed for the needs of financial traders. Trading turrets enable users to visualize and prioritize incoming call activity from customers or counter-parties and make calls to these same people instantaneously by pushing a single button to access dedicated point-to-point telephone lines (commonly called Ringdown circuits). In addition, many traders have dozens or hundreds of dedicated speed dial buttons and large distribution hoot-n-holler or Squawk box circuits which allow immediate mass dissemination or exchange of information to other traders within their organization or to customers and counter-parties. Due to these requirements many Turrets have multiple handsets and multi-channel speaker units, generally these are shared by teams (for example: equities, fixed income, foreign exchange) or in some cases globally across whole trading organizations.
Unlike standard Private Branch Exchange telephone systems (PBX) designed for general office users, Trading turret system architecture has historically relied on highly distributed switching architectures that enable parallel processing of calls and ensure a "non-blocking, non-contended" state where there is always a greater number of trunks (paths in/out of the system) than users as well as fault tolerance which ensures that any one component failure can not affect all users or lines. As processing power has increased and switching technologies have matured, voice trading systems are evolving from digital time-division multiplexing (TDM) system architectures to Internet Protocol (IP) server-based architectures. IP technologies have transformed communications for traders by enabling converged, multimedia communications that include, in addition to traditional voice calls, presence-based communications such as: unified communications and messaging, instant messaging (IM), chat and audio/video conferencing.
Example of some of the major telephony key systems include:
- Speakerbus iTurret dealerboard
- Unify OpenScape XPERT IP Touch Screen 
- BT Netrix.
- Mitel/Wesley Clover Solutions 5560 IP Turret
- Infinet Financial Systems Adaptive Trading Platform
- IP Trade 
- Etrali Trading Solutions Open Trade
- Green Key Technologies 
- Electronic trading platform
- Dedicated line
- Stock market data systems
- Straight-through processing (STP)
- Trading system
- Trading room
- "Speakerbus iturret dealerboard". Speakerbus SIP dealerboard Website. 2011-04-01. Retrieved 2011-10-04.
- "Speakerbus". Corporate Website. 2011-04-01. Retrieved 2011-04-01.
- Unify Corporate Website
- BT Unified Trading
- Wesley Clover Solutions
- Infinet Corporate Website
- http://www.linx-networks.com "IP Trade". IP Trade Corporate website. 2012-05-30. Retrieved 2012-05-30.
- "Etrali Trading Solutions Open Trade turret". Corporate Website. 2013-07-18. Retrieved 2010-11-23.
- "Green Key Technologies". Corporate Website. 2014-04-24. Retrieved 2014-04-24.
- A Bankers Guide to Trading Turrets, Peter Redshaw, 12 September 2013. Gartner.