For sale here is 1 - Comrex Blue Box digital audio transmission device for analog telephone lines, in perfect working and good cosmetic condition. It comes with its original power supply unit that came with it from Comrex.

From the manufacturer:

"The Comrex BlueBox is a digital audio transmission device for analog telephone lines. The BlueBox allows wideband, broadcast quality audio over normal “toll quality” telephone circuits"

Specifications:

• Full duplex FM quality (15 kHz) audio bandwidth at connect rates of 24 kb/s and above.
• Full duplex audio scales from 12.7 kHz to 4.7 kHz at connect rates of 21.6 kb/s to 9.6 kb/s.
• Separate “Voice Mode” allows 7 kHz audio with a 300 BAUD ancillary data channel and extra forward error correction.
• Easy to use dialing and configuring interface.
• Automatically connects at highest possible rate supported by telephone connection.
• Monitors line quality and renegotiates should line degrade.
• Two tally closures (one on connection, one triggered by the user).
• Ability to work with a Comrex HotLine, Vector or Matrix.
• Can store 19 telephone numbers and last number dialed in nonvolatile memory.
• Short coding delay (100 mS) allows seamless two-way conversation.

A copy of the user manual can easily be found online.

This is a great price for a quality codec. Don't miss out on this opportunity to add this to your system!