Ran into an interesting problem. Samsung VOIP phones, for example the SMT-i5210, have a PNP [Plug In Play] mode. If DHCP is setup with the correct optional parameters, you can have the phone pick up the Samsung phone system’s IP address from the DHCP parameters. Samsung calls this “PnP use for IP AOM registration”.

To setup DHCP to do this, you need to add two DHCP generic options:

Option 66 – This must be set to a string value of “SEC_ITP”. It tells the Samsung phone the DHCP server is a valid Samsung sending server. From the Samsung docs, “This option is used to distinguish our DHCP server from the other one under the circumstance one more DHCP servers are running”.

Option 128 – This is the IP address of the Samsung phone system. For example, if your Phone LAN is 10.2.1.x/24 and the phone system is on 10.2.1.201, you would enter 10.2.1.201 for this parameter.

Side note: In Sonicwall, you create each option under the “DHCP Generic Option Group: Create new DHCP Option Object…”, then put them into a group using “DHCP Generic Option Group: Create new DHCP Option Group…” so both Option 66 and Option 128 are transmitted.

So, in reality, Samsung is using the TFTP server IP address to pull the Samsung Phone System’s IP address.

Now, when you reboot the Samsung VOIP phone, make sure to put it in PNP mode as well as DHCP dynamic. The Samsung VOIP phone will now pick up the IP address of the Samsung Phone system automatically. On the Samsung Phone side, you would control and match the extension based on the MAC address of the Samsung VOIP phone. Nice part, people can move their Samsung VOIP phone to another office and Samsung Phone system will allow the phone extension to follow the physical phone.