Anybody know where I can buy 420 handsets? Need about 6 for a customer to have on hand. Thanks.

Have you tried Sundance, click on the Equipment button at the top of the page.

That was my first thought!! I clicked on "equipment", but only found whole phones. I would try phoning, but I'm on hold with NEC tech support! Which reminds me, I think I'll go to the "Nitsuko" topic and post my question there.

Try https://www.graybar.com they carry replacement handsets made by Walker.