Maximum Number of Option 66 IP Addresses for Cisco IP SCCP Phone

A.

References: http://www.techtronicssolution.com/blog/?p=1201

Cisco IP SCCP phones use the DHCP option 66 to receive the IP address of the TFTP server from which they can download the firmware and configuration files. The maximum number of option 66 IP addresses that a Cisco IP SCCP phone will accept and use from a DHCP server depends on the specific model of the phone and the firmware version it is running.

Generally speaking, most Cisco IP SCCP phones support up to 4 option 66 IP addresses that can be provided by a DHCP server. However, there are some older phone models that may only support up to 2 option 66 IP addresses, while newer phone models may support up to 5 option 66 IP addresses.

It's worth noting that even if a Cisco IP SCCP phone is configured with multiple option 66 IP addresses, it will only use the first one that it can successfully reach. This means that if the phone is unable to download the firmware or configuration files from the first TFTP server specified in the option 66, it will attempt to download them from the second server specified, and so on until it is successful.

In summary, the maximum number of option 66 IP addresses that a Cisco IP SCCP phone will accept and use from a DHCP server varies depending on the phone model and firmware version, but most phones support up to 4 option 66 IP addresses.