Before doing in depth analysis that will take time, please do the following quick tests:
1) Check the line balance and client status
2) Reboot the phone (unplug and plug the phone). Make sure the internet is being plugged into internet and not to the slot that is marked pc. And it is getting power.
3) Check the internet speed using following
i) Please use firefox or IE.
ii) Select Codec G729
iii) Number of lines 5
b) If the internet is bad, contact the internet provider
4) Check firewall:
a) on myspeed.visualware.com choose VoIP as the test type
b) Choose VOIP as the test type
c) If certain ports are open. This only test a small range of port. We will be providing a custom tester to test the full range soon.
d) If any of the ports are blocked, please contact the network engineer