I have two Grandstream GXP2000 hardphones that power on (the LEDs all come on green), but the display is blank, and the switch doesn't recognize the phones as being connected.
In the past, this has happened, except the phones still responded to the network, so I was able to reboot them using the web interface, and they worked again. Simply unplugging it, and plugging it back in doesn't help. I can't reset it to the factory settings, because the display is blank.
I am fairly certain that the phone is the problem, since I have plugged known good phones into the same power and network connections, and they worked. Likewise, the bad phones connected to known-good power and network don't work.
From what I have read online, it sounds like this might be a common problem, but I thought I'd ask here to see if anyone knows any tricks.
From my experience, the GXP handsets were the worst I've ever used. I found much better results using their ATA converter and a cheap £5 handset.
I had problems with the shocking web interface not loading, phones not registering, NAT issues, STUN issues all sorts.
May seem slightly ostentatious but I'd replace them all for SPA941 or 942. You'll have much more fun using them than trying to keep them online :)