My remaining problem is to interface with the phone system, remotely pick up the ringing line, hold a conversation, conference in a supervisor if necessary and then terminate the call. Support for only one call at a time is needed. No other functions are required from the phone system.

This would be an exact fit for the discontinued Transtalk cordless phone. I know you don't want a "one of" solution given that you have multiple locations, that is why I am suggesting an off the shelf solution. I also know that you prefer this to operate with the existing wireless PDAs but I don't think that is going to be possible.

I don't know the extent of your resources or what you want to spend on this but given the extent of your operation you might be able to have systems custom made. Line cards are readily available for PCs that can interface it as a single line analog device to the partner extension ports. An application could then be written to do what you want.

-Hal

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