cisco 3911 phone failed to register with sip server

1. Brekeke Product Name and Version: SIP server 3.3.4.4

2. Java version:

3. OS type and the version: windows xp sp3

4. UA (phone), gateway or other hardware/software involved: cisco 3911

5. Your problem:
My cisco 3911 phone doesn`t seem to register with SIP server. Does it need any special configuration or it's only my fault?
Thanks in advance.

Did you create a user in the SIP server's [User Authentication] page?

If you did, are you using the correct username and password in the phone?

Hi thanks.

Yes I did the server part.
I think the problem is on the phone side, phone configuration is not so straighforward as expected.
But I will keep trying since I understand from your comment that it should work.

If you try another phone such as X-lite softphone, does the same problem happen?

Yes, X-lite works right.
I will give another try to the cisco this afternoon.

Edited after somr¡e toiling around with the phone:
I can manually change network config (IP, mask, routerIP, etc) by disabling DHCP, but the SIP configuration tab (user, auth,...) does not allow me to edit anything...

It seems a configuration issue at Cisco phone.

Does the Cisco phone get any SIP response from the Brekeke SIP Server?

Can you see Cisco phone's REGISTER activities in the SIP Server's [Dial Plan]->[History] page?