Right Click IPV4 DHCP server and Set Predefined options.
Click on Add, Specify a Name like Phone System TFTP , Data Type= IP Address, Code=150 and a description. Press OK and specify a IP Address of TFTP Server
Navigate to the scope where you would like to add option 150 and Right Click Scope Options -> “Configure Options” and Select “150 Phone system TFTP” and then OK
This will add Option 150 for the Scope
Requirements: DHCP Service
If you would like to add a DHCP Service into a Windows 2k8 Server, open Server Manager (Start->Admin Tools-> Server Manager), right click Roles and Add Roles.