I managed to find the manual, but it does not say a thing about this. I think your provider has to give you the information, with the incoming call. When he switched that information of, your phone can't display it. Sometimes the providers charge you extra for that service. If, on the same extension, another phone did display the number, perhaps hetre is a way to switch it on, but I could not find it.
The link is to the manual.
http://ipf.msu.edu/_files/pdfs/user-guides/norstar-t7208.pdf
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