Cisco SPA2102-SF Administration Guide - Page 35

Introducing Cisco Small Business Analog Telephone Adapters ATA Software Features 1 Feature DHCP Renewal on Timeout Description SPA2102, SPA3102, and PAP2T voice devices typically operate in a network where a DHCP server assigns IP addresses to the devices. Because IP addresses are a limited resource, the DHCP server periodically renews the device lease on the IP address. Therefore, if an ATA device loses its IP address for any reason, or if some other device on the network is assigned its IP address, the communication between the SIP proxy and the device is either severed or degraded. Whenever an expected SIP response is not received within a programmable amount of time after the corresponding SIP command is sent, the DHCP Renewal on Timeout feature automatically causes the device to request a renewal of its IP address. If the DHCP server returns the IP address that it originally assigned to the device, the ATA device is presumed to be operating correctly. If it returns a different address, the ATA device changes its IP address to the new address provided by the DHCP server. The ATA device then resets, and once again sends a SIP register request for the DHCP server to accept. Cisco Small Business ATA Administration Guide 35