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Sonifex CM-TLL - Line Powered Telephone Line Listen Unit

by Sonifex
£341.94 inc. vat
£284.95 ex. vat
Please contact us for availability.

Sonifex CM-TLL

The Sonifex CM-TLL provides a low-loss interface to receive audio from a telephone line. The line-powered unit is compatible with all analogue direct exchange lines and includes an LED indication of incoming calls. The unit is intended to be used with an earpiece amplifier to receive an audio feed by telephone from a studio.

The line and telephone set are connected to the unit via the RJ11 connectors in order to make an outgoing call. A telephone may not be required if calls are only incoming, because telephone line ringing is indicated by a flashing LED built into the unit. In either case, the ‘LINE CONNECT’ switch is pressed to make the line connection. The ‘ON’ LED indicates that the unit is powered and that audio is routed from the line to the XLR plug.

Sonifex CM-TLL Features

  • Audio interface to direct analogue exchange lines - receive calls with electrical isolation from the line.
  • Line powered, requiring no battery or external power.
  • LEDs indicating ‘Ring’ and ‘On Hold’ conditions.
  • Loop-through line sockets provide in-line connection with existing telephone.
  • Existing telephone remains connected when the unit is in use.
  • Line connections to British or International sockets via supplied cable kit.
  • Connection to the telephone set is maintained while the unit is in use.
  • Small, rugged extruded aluminium case with XLR3 male 4-wire connector.

Sonifex CM-TLL Specifications

4-Wire Output

  • Output Impedance: 150Ω, transformer coupled
  • Output Connector: 3 pin XLR male connector
  • Output Level: Typically 0dBU for average line level   


  • Off Hook Voltage: 6V minimum
  • 2 Wire Connectors:
    • RJ11 socket - line
    • RJ11 socket - handset   

Front Panel Operational Controls 

  • Line Connect: Push button with indicator
  • Ring LED: Indicates incoming ringing
  • On LED: Indicates connection to the telephone line      

Physical Specification 

  • Dimensions:
    • 77mm (W) x 83mm (D) x 42mm (H) 
    • 3.0” (W) x 3.3” (D) x 1.7” (H)
  • Weight:
    • Nett: 0.20kg Gross: 0.70kg
    • Nett: 0.50lbs Gross: 1.6lbs