I want to add a wireless phone to my old Norstar phone system.  20 years ago, I was told the wireless option was not worth the price and was junk.

I see these new offerings, and wondering if something like this T7406e wireless handset would plug in and replace a T7028 desk phone.

We do have wireless headsets, which work well - but in this case I just want a wireless handset.  Can I do it?  These old Norstar systems are bullet proof, so at this time I do not want to replace the heart of the system or go full IP phones.

This is the T7406e -

Our existing T7028s -


And our existing phone system -

We have those wireless handsets in our shop.  You were told correctly, they are way overpriced and are junk.  
If the two shop foremen get their handsets to last more than three months before they shit the bed, it's considered a good quarter.  

You are correct, the backbone of the system with the desk phones works great, but those wireless phones are a joke.  
Unless you can get some sort of maintenance contract that offers free replacement when they break, I wouldn't go that route.