Secure voice server condenses telephone calls to save up to 80 percent bandwidth

TimePlex Federal Systems of Washington has designed a Secure Telephone Unit III Secure
Voice Server to reduce by as much as 80 percent the bandwidth taken up by STU III
telephone calls.


The server converts the phone’s analog output to a 9.6-Kbps digital signal that
consumes less than one-fifth the capacity of a standard voice line. As many as five secure
calls can travel over the line at once.


STU III is the federal standard for secure telephone communications at military, law
enforcement and intelligence agencies. The dedicated phone unit digitizes and encrypts
voice input, then modulates the signal back to analog for transmission over switched
circuits at 56 Kbps.


The TimePlex server bundles the encrypted 9.6-Kbps digital signal with as many as four
others, said Les Wallace, product marketing manager for TimePlex. Transmission rates of
2.4 Kbps, 4.8 Kbps or 9.6 Kbps are negotiated during call setup between STU III phones.


The voice server comes standalone or as a module for the TimePlex Link server family.
It supports 12 to 144 secure lines in any combination of 4.8- or 9.6-Kbps calls. The
server starts at $15,000, or $1,250 per port.


Wallace said the voice server can extend capacity of existing networks when additional
bandwidth is too expensive or not available.


He said the Navy is evaluating it for a carrier battle group that has limited
bandwidth. Up to 144 secure STU III calls could cross a T1 line compared with the normal
24 voice calls.


Contact TimePlex at 800-342-5837. 

About the Author

William Jackson is a Maryland-based freelance writer.

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