48-6
Cisco ASA 5500 Series Configuration Guide using the CLI
Chapter48 Configuring the Cisco Phone Proxy
Prerequisites for the Phone Proxy
Prerequisites for the Phone Proxy
This section contains the following topics:
•Media Termination Instance Prerequisites, page48-6
•Certificates from the Cisco UCM, page 48-7
•DNS Lookup Prerequisites, page 48-7
•Cisco Unified Communications Manager Prerequisites, page48-7
•Access List Rules, page 48-7
•NAT and PAT Prerequisites, page 48-8
•Prerequisites for IP Phones on Multiple Interfaces, page 48-9
•7960 and 7940 IP Phones Support, page48-9
•Cisco IP Communicator Prerequisites, page 48-10
•Prerequisites for Rate Limiting TFTP Requests, page48-11
•About ICMP Traffic Destined for the Media Termination Address, page48-11
•End-User Phone Provisioning, page 48-12

Media Termination Instance Prerequisites

The ASA must have a media termination instance that meets the following criteria:
•You must configure one media termination for each phone proxy on the ASA. Multiple media
termination instances on the ASA are not supported.
•For the media termination instance, you can configure a global media-termination address for all
interfaces or configure a media-termination address for different interfaces. However, you cannot
use a global media-termination address and media-termination addresses configured for each
interface at the same time.
•If you configure a media termination address for multiple interfaces, you must configure an address
on each interface that the ASA uses when communicating with IP phones.
For example, if you had three interfaces on the ASA (one internal interface and two external
interfaces) and only one of the external interfaces were used to communicate with IP phones, you
would configure two media termination addresses: one on the internal interface and one on the
external interface that communicated with the IP phones.
•Only one media-termination address can be configured per interface.
•The IP addresses are publicly routable addresses that are unused IP addresses within the address
range on that interface.
•The IP address on an interface cannot be the same address as that interface on the ASA.
•The IP addresses cannot overlap with existing static NAT pools or NAT rules.
•The IP addresses cannot be the same as the Cisco UCM or TFTP server IP address.
•For IP phones behind a router or gateway, you must also meet this prerequisite. On the router or
gateway, add routes to the media termination address on the ASA interface that the IP phones
communicate with so that the phone can reach the media termination address.