If your phone is using a Wi-Fi connection make sure that Wi-Fi is enabled and connected properly before network settings can be obtained. See more information here.
Static IP vs DHCP
If the automatic process fails or if your network does not use DHCP you will have to configure the phone's network settings manually using a static IP address. Manual network configuration can be performed from either the phone user interface or the web user interface.
Generally speaking, DHCP is more secure than a static IP address since the IP address is constantly changing. There are, however, certain situations where you would need to know the specific IP address of a phone (for example configuring constant network or firewall settings for the phone) making a static IP a more functional choice.
Contact your network or IT administrator to find out the required network values (IP address, subnet mask, default gateway address, and DNS address). The phone supports both the IPv4 and IPv6 address formats (IPv4 is enabled by default.) You can also switch a static IP configuration back to DHCP.
Phone User Interface
With the phone user interface, you can configure a Static IP address or switch a static IP back to DHCP.
To configure a static IP address:
Select Menu from the idle screen and navigate to Advanced > Network > WAN Port. If prompted for a password enter "admin" or the current administrator password.
Depending on the addressing format of your network, set the value in the IP Mode field to IPv4, IPv6, or IPv4 & IPv6.
If you selected IP4 (or IPv4 & IPv6), select the IPv4 field and select Static IPv4 Client.
If you selected IP6 (or IPv4 & IPv6), select the IPv6 field and select Static IPv6 Client.
Enter the desired values in the IP Address, Subnet Mask, Default Gateway, Pri.DNS and Sec.DNS fields respectively.
On the T57 you can use the full onscreen keyboard. On the T54 you can use the keypad to enter the colon character (:) for separating values in each field, press the asterisk (*) several times.If your company doesn't use a private DNS, Google’s public DNS server (address 8.8.8.8) is a popular choice for the primary DNS, but there are plenty of other options that might work faster for you. The secondary DNS is optional.
Select Save to accept the changes.
To switch a static IP address to DHCP mode:
Select Menu from the idle screen and navigate to Settings > Network > WAN Port.
Depending on the existing configuration select either the IPv4 or IPv6 field.
Select DHCP and select Save to accept the changes.
Web User Interface
Configuration via the web user interface is only possible if your phone has previously been able to obtain an IP address automatically or by a provisioning process. It is useful for switching between DHCP and Static IP modes.
To configure the network via the web user interface:
Access the web user interface as described here.
Select the Network tab on the top and the Basic options from the side.
Depending on the addressing format of your network, you can select or change the Mode (IPv4/IPv6) drop-down menu to either IPv4, IPv6, or IPv4 & IPv6.
If a static IP is already configured and you want to switch to DHCP, select DHCP under the IPv4 Config or IPv6 Config section.
If DHCP is selected and you want to set up a static IP instead:
Depending on your selection in the Mode IPv4/IPv6 field, select Static IP Address under the IPv4 Config or IPv6 Config section.
Enter the desired value in the IP Address, Subnet Mask, Default Gateway, Primary DNS, and Secondary DNS fields respectively.
If your company doesn't use a private DNS, Google’s public DNS server (address 8.8.8.8) is a popular choice for the primary DNS, but there are plenty of other options that might work faster for you. The secondary DNS is optional.
You can also use a dynamic DNS by selecting OFF in the Static DNS field.
A Dynamic DNS lets you use an easy-to-remember "static" domain name even when DHCP is enabled. It can be helpful if a static IP is not available to you but it does require you to register with a DDNS provider before you can use it.Click Confirm to accept the changes.