A properly registered phone will look like this, with date, time, and extension number displayed across the top:

If the display says “Register Failed!”, it means that the phone is connecting to the server, but it’s login information is correct (extension number does not exist, “IP Extension” is not enabled for that extension, etc.)  In this scenario the phone has had communication with the server, and the sever is rejecting registration

Depending on firmware version, an incorrect password may receive “Register Fail!” or the message, “Press #27[Enter]”.  By keeping the phone on hook, and dialing #27, followed by the enter key, the phone will prompt for extension number and password. Note that when you enter #27, it deletes the previously configured extension and password from the phone. 

If the display continually reads “Registering…” but is never successful, and never shows “Register Failed!”, it means that the phone is not communicating with the server. 

The actual login function of the phone is not a SIP REGISTER method, but an XML transaction on TCP port 10032.  If the server determines that the phone is behind NAT from the server, then it will send an XML message to the phone instructing the phone to REGISTER.  If the phone has problems with this, it will display the date, time, and extension number on the top row, and “SIP REG FAIL!” on the second row.  This problem could be caused by firewall proxy, etc.  (In the case of the example photograph, a block rule was added to the firewall to simulate this error):

If the phone is properly registered, and you dial ##, a call should start. The screen will look like below.  You should hear the operator state “This is the AltiGen voicemail system….”  If that is not happening, it is important to look at the upper right hand corner of the display to see if the counter for the call is displayed or not.  If the counter is displayed, and incrementing correctly, then the SIP portion of the call setup should be correct, however the SDP may be incorrect, or possibly there are no voice resources assigned to the server’s HMCP board.  If the call counter does not appear, then there is a problem with the SIP communication between the phone and the server.  The likely causes for this are SIP ALGs or SIP Proxys on intermediary firewalls, or SIP NAT support in AltiGen’s Enterprise Network Manager not being configured properly (either disabled when it should be enabled, enabled when it should be disabled, configured with the wrong public IP address, an IP network configured as “Local” when it is not in the same NAT realm as the server, etc.)