Recent support tickets have caused me to look a little more into how these LG phones work. You may assume they are SIP phones but they are not. It’s almost as though LG took a digital phone and just made it run on IP.
SIP is a very feature poor protocol, so SIP phones tend to contain a lot of features operated by the phone itself. There is very little communication back to the central server. You dial digits on the phone and then press send and at that point a message is sent to the server.
These LG phones depend on constant contact with the host PBX. If the internet connection is not present then pressing any key on the phone does not work. The phone must send every single key press to the PBX and receive an acknowledgment back before it updates the display. Whilst a SIP phones can tolerate minor internet outages when they are idle and will still let you dial a number, even if waiting for a few seconds for the connection to return, the IPecs phones have no tolerance at all. If the network connection is out for a second, you can’t get any key to respond in that second.
The upshot of this is that if your customer calls and says the buttons on the phones are not responding, don’t assume a problem with the phone. It’s more likely to be a network issue. Congested networks where UDP packets get lost also display the same behaviour.
When I tested I also found that after about 5 minutes with no internet connection the phone did a reboot. If the connection was down during the reboot, the phone does not come up. The internet has to be on during boot up for the connection to be restored.
John Rogers
