Topex VCSS

Voice communication system intended for air traffic control applications and dispatcher - type communication centers. Full digital system, flexible and scalable architecture to allow its configuration for a very wide range of applications in the ATC/ATM field. The system allows the operators (dispatchers) to access terrestrial phone lines, radio channels, intercoms and paging functions. It can also be equipped with a voice recorder system.


  • Real systems for voice communications for ACC, APP, TWR.
  • Simulated systems for voice communications (for training and evaluation) ACC, APP, TWR.

Services for Phone lines:

  • Direct access to outgoing and ingoing lines
  • Intercommunication between consoles
  • Dialing again the last number
  • Access with selection(composing a number)
  • Direct access to local extensions (DISA)
  • Barging in over busy
  • Call transfer
  • Call parking
  • Dial tone (tone for making a call)
  • Redial on BL line
  • Paging feature (transmission of the messages through the speakers network)
  • Conferencing with max. 8 ports

Services for Radio lines:

  • Monitor : Any of the channels allocated to a position can be selected for monitoring by itself or together with a number of channels (up to 64 channels). The other operators could select for monitoring some channels in any combination.
  • Frequency transmission: By selecting a radio channel for transmission, you will achieve both reception and transmission on the respective channel. The monitoring function may remain active. During transmission, the reception for neighbour radio equipment is inhibited, in order to avoid microphone effects.
  • Cross coupling: Allows working through a group of radio channels at the same time. The transmission from one operator position is sent to all channels in group, while the reception of one radio channel is sent again to the other radio channels in the group.
  • Best Signal Selection: The BSS function selects automatically the "BEST" receiver from a group of receivers (up to 64).The selection is achieved through a complex algorithm, based upon signal power and stationary characteristics.
  • If there's no voice signal on the selected frequency (there's only voice), the signal will interrupt not to disturb the operator.


C21 Communications provides solutions and products designed to reduce the cost of telephony for SoHo and SME businesses, right through to global enterprises.

C21 Communications Ltd. Harwell International Business Centre, 173 Curie Avenue, Harwell, Didcot, Oxfordshire, OX11 0QG.


Contact Number: +44 1235 838592