IP Phones using DHCP options for TFTP
When deploying Cisco Phones and Call Manager, it may be desirable for the phones to automatically discover the TFTP server/Call Manager in order to download a configuration. This will happen automatically when phones are in the same broadcast domain as the Call Manager Server. However, if your Call Manager server is in a different network, you may need to specify a TFTP server.
This article explains how to specify a TFTP server using DHCP options.
Per Cisco's requirements you may need to enable DHCP Option 150 so that in the DHCP broadcasts, phones can also see a list of all TFTP servers that are connected to the network. The following instructions explain how to configure DHCP options for a VLAN on an MX Security Appliance, Z-series Teleworker Gateway, or layer 3 MS switch:
- Navigate to Security appliance > Configure > DHCP (or, for an L3 MS switch, Switch > Configure > Routing & DHCP > [interface whose DHCP scope is to be altered] > DHCP settings).
- Add a DHCP option by selecting the Option drop-down and choosing Custom.
- Add the Code, in this case, 150; choose the Type to be IP, and put the IP address of the TFTP server in the Value as per the example below:
