This is what I did on the Phone. I follow some instruction I found on this forum as well. This is what I did.

1. I Disable DHCP Mode

2. I assign IP Address for local network eg. below
IP Address: 192.168.100.100
Subnetmask: 255.255.255.0
Gateway: 192.168.100.1

3. I Assign SIP Server Address (Sip Server Address & URI)
1st SIP Server (192.168.101.50 SV8100 from 10-12-09)

4. Then I change the port to 5080

5. I press Exit and Save
The phone reboots but it says server not found.
Is there anything that I missed. Please advice thanks.