Gary,
Let's establish a few things: (from a voice perspective)
1) Cordless referes to technology like DECT, so that there is no "ambilical cord" from/to the phone unit - the base station, to the handheld device. These are marketed under the Siemens, Gigaset, etc brandnames. Nice to have, and plug into a conventional old style analog line from Telkom.
2) Wireless referes to technology like GSM, CDMA etc, where the device is a base station all-in-one device. It "talks" without wires to the tower, like a cell phone and also Neotel.
I would think that if you have a Neotel device that is marketed as a consumer device, you could have the latter - no chance of connecting this to your PABX as it probably needs an analog line.
I believe Neotel may have a device for you, called Neoflex Voice. The last i checked, this is not sold directly by Neotel, but by guys like Samsung. I stand to be corrected. Hope this helps.