Chapter 17 Configuring the Cisco Phone Proxy

Phone Proxy Guidelines and Limitations

format: SEP<mac_address>.cnf.xml. If the device name does not follow this format

(SEP<mac_address>), CIPC cannot retrieve its configuration file from Cisco UMC via the phone proxy and CIPC will not function.

•The phone proxy does not support IP phones sending SCCP video messages using Cisco VT Advantage because SCCP video messages do not support SRTP keys.

•For mixed-mode clusters, the phone proxy does not support the Cisco Unified Call Manager using TFTP to send encrypted configuration files to IP phones through the ASA.

•Multiple IP phones behind one NAT device must be configured to use the same security mode.

When the phone proxy is configured for a mixed-mode cluster and multiple IP phones are behind one NAT device and registering through the phone proxy, all the SIP and SCCP IP phones must be configured as authenticated or encrypted, or all as non-secure on the Unified Call Manager.

For example, if there are four IP phones behind one NAT device where two IP phones are configured using SIP and two IP phones are configured using SCCP, the following configurations on the Unified Call Manager are acceptable:

–Two SIP IP phones: one IP phone in authenticated mode and one in encrypted mode, both in authenticated mode, or both in encrypted mode

Two SCCP IP phones: one IP phone in authenticated mode and one in encrypted mode, both in authenticated mode, or both in encrypted mode

–Two SIP IP phones: both in non-secure mode

Two SCCP IP phones: one IP phone in authenticated mode and one in encrypted mode, both in authenticated mode, both in encrypted mode

–Two SIP IP phones: one IP phone in authenticated mode and one in encrypted mode, both in authenticated mode, both in encrypted mode

Two SCCP IP phones: both in non-secure mode

This limitation results from the way the application-redirect rules (rules that convert TLS to TCP) are created for the IP phones.

Media Termination Address Guidelines and Limitations

The phone proxy has the following limitations relating to configuring the media-termination address:

•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 ASA; 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.

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ASA Services Module, ASA 5555-X, ASA 5545-X, ASA 5585-X, ASA 5580 specifications

Cisco Systems has long been a leader in the field of network security, and its Adaptive Security Appliance (ASA) series is a testament to this expertise. Within the ASA lineup, models such as the ASA 5505, ASA 5580, ASA 5585-X, ASA 5545-X, and ASA 5555-X stand out for their unique features, capabilities, and technological advancements.

The Cisco ASA 5505 is designed for small businesses or branch offices. It provides essential security features such as firewall protection, flexible VPN capabilities, and intrusion prevention. The ASA 5505 supports a user-friendly interface, allowing for straightforward management. Its built-in threat detection and prevention tools provide a layered defense, and with scalability in mind, it can accommodate various expansion options as organizational needs grow.

Moving up the line, the ASA 5580 delivers greater throughput and advanced security features. This model is suited for medium to large enterprises that require robust protection against increasingly sophisticated threats. Its multi-core architecture allows it to manage high volumes of traffic seamlessly while maintaining excellent performance levels. The ASA 5580 also supports application-layer security and customizable access policies, making it highly adaptable to diverse security environments.

The ASA 5585-X further enhances Cisco's security offerings with advanced malware protection and extensive security intelligence capabilities. It incorporates next-generation firewall features, including context-aware security, and supports advanced threat detection technologies. This model is ideal for large enterprises or data centers that prioritize security while ensuring uninterrupted network performance and availability.

For enterprises requiring a balance of performance and security, the ASA 5545-X presents a compelling option. This model features scalable performance metrics, high availability, and integrated advanced threat protection. Coupled with advanced endpoint protection and detailed monitoring capabilities, the ASA 5545-X enables organizations to manage their security posture effectively.

Lastly, the ASA 5555-X blends cutting-edge technologies with strong security infrastructures. It boasts high throughput and the ability to execute deep packet inspections. Its sophisticated architecture supports threat intelligence feeds that provide real-time security updates, making it a powerful tool against modern threats.

Each of these Cisco ASA models brings specific advantages to varied environments. Their integrative capabilities enable businesses to enhance their security postures while benefiting from seamless scalability and management. As cybersecurity threats evolve, these advanced appliances play a vital role in protecting valuable digital assets.
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