The item shown is just the interface box. The Pro 300 series Technical Manual describes the whole system it consists of three parts, the one shown in the Ebay entry is one of the three the Voice unit , which is basically a speakerphone box with some extra buttons on it that the software can see. Not clear if the other two parts, which are the important ones, are included in the offer. paul On May 20, 2014, at 1:04 PM, lee.gleason at comcast.net wrote: If anyone out there is hankering to have one, a DEC PRO telephone Voice Unit is on Ebay right now. http://www.ebay.com/itm/NASA-Digital-DEC-DTC11-B-Voice-Unit-Professional-30…