Symptoms: On a late-model Grandstream phone the status light is red, you cannot make or receive calls, and the display says "Account not registered." Other phone brands may have different messages, but in all cases, the line light will be red and the phone is unable to make/receive calls.
This indicates that the phone can't reach us. The first step is to reboot the phone by removing power and then reconnecting it. If that doesn't fix it, then see these possible causes:
1. The network cable is in the wrong port on the phone. It must be in the LAN or SW port, not the PC port.
2. The network switch port or cable is bad. Try it on another port/cable. For example, move the phone to another office with a known working phone and cable.
3. Router or DNS problem at the site. If this is a home or very small office, the router is probably a basic home/small office router, and they often just need to be rebooted. This means rebooting the cable or DSL modem, the router, and any switches or other devices. Then reboot the phone.
4. It is unlikely, but possible that the settings have become corrupt in the phone. You can try a factory reset and reconfiguration. You should contact us first, however, to work with you on this. DO NOT factory reset a phone without contacting us first.
5. Phone has failed. If everything above checks out, we can assume a failed phone and would need to replace it.