Cisco ASA 5505 Configuration Manual page 963

Chapter 43 Configuring the Cisco Phone Proxy
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Media Termination Address Guidelines and Limitations
The phone proxy has the following limitations relating to configuring the media-termination address:
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Configuring the Phone Proxy
This section includes the following topics:
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OL-20339-01
When the adaptive security appliance is used with Unified Communications Manager Express
(Cisco UCME), Directory Services does not work on remote IP phones that register with Cisco UME
through the adaptive security appliance. This limitation occurs because the adaptive security
appliance requires HTTPS.
When the adaptive security appliance is used with Unified Communications Manager Express
(Cisco UCME), the phone proxy does not support remote IP phones configured with MTP and G729
codec option for media. G729 is supported; however, this configuration results in one way audio
when both IP phones used in the call are remote.
The phone proxy does not support displaying the lock icon on IP phone screens. IP phones display
the lock icon on the phone screen during encrypted calls. Even though the lock icon is not displayed
on the screen, the IP phone call is still encrypted because the phone proxy encrypts calls by default.
When configuring the media-termination address, the phone proxy does not support having internal
IP phones (IP phones on the inside network) being on a different network interface from the Cisco
UCM unless the IP phones are forced to use the non-secure Security mode.
When internal IP phones are on a different network interface than the Cisco UCM, the IP phones
signalling sessions still go through adaptive security appliance; however, the IP phone traffic does
not go through the phone proxy. Therefore, Cisco recommends that you deploy internal IP phones
on the same network interface as the Cisco UMC.
If the Cisco UMC and the internal IP phones must be on different network interfaces, you must add
routes for the internal IP phones to access the network interface of the media-termination address
where Cisco UMC resides.
When the phone proxy is configured to use a global media-termination address, all IP phones see
the same global address, which is a public routable address.
If you decide to configure a media-termination address on interfaces (rather than using a global
interface), you must configure a media-termination address on at least two interfaces (the inside and
an outside interface) before applying the phone-proxy service policy. Otherwise, you will receive an
error message when enabling the Phone Proxy with SIP and Skinny Inspection.
The phone proxy can use only one type of media termination instance at a time; for example, 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.
Task Flow for Configuring the Phone Proxy, page 43-14
Creating the CTL File, page 43-14
Adding or Editing a Record Entry in a CTL File, page 43-15
Creating the Media Termination Instance, page 43-16
Creating the Phone Proxy Instance, page 43-17
Adding or Editing the TFTP Server for a Phone Proxy, page 43-19
Cisco ASA 5500 Series Configuration Guide using ASDM
Configuring the Phone Proxy
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