The Tone Commander 6220T-TSG-DD and 6220U-TSG-DD are on-hook secure versions of the 6220 ISDN Telephone. These models meet the requirements for TSG-6 certification set by the National Telecommunications Security Working Group. All appropriate electronic circuitry has been modified to ensure the 6220-TSG models meet TSG-6 on-hook security measures.

Both TSG models are equipped with 20 keys.

The phones are supplied with the TSG-DD1 Disconnect Device, which completely disconnects the ISDN line from the phone when power is not applied.

Teo TSG-6 products meet the requirements of the Intelligence Community Technical Specification ICD/ICS 705 for Sensitive Compartmented Information Facilities (SCIF), prepared by the National Counterintelligence Executive, which replaced DCID 6/9. Please refer to TSG-6 Guidelines.