Cisco SPA2102-AN - Single Port Router Administration Manual page 35

Introducing Cisco Small Business Analog Telephone Adapters
ATA Software Features
Cisco Small Business ATA Administration Guide
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.
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