Nothing within the PBX can do that. The only component with the ability to route based on the caller ID would be an IPEdge voicemail. If your system is 20 years old then you probably have a Stratagy voicemail system. These voicemail did not have this ability either.

The Toshiba PBX system is pretty limited to mostly basic call routing. Anything with more advanced features required something with more processing ability. For example, the MAS is a PC based application server that you could use for a voicemail system or Automatic Call Distribution (ACD). There was also a Call Routing application. All these would require a MAS with the appropriate licenses.

The IPdge PBX and application server could route incoming calls based on caller ID. It may not be possible to add an IPEdge to your system depending on the processor and licenses on your current system.

I agree that the Toshiba system is pretty rock solid. It was a shame to see it shut down.