Chapter 4 Basic and Additional SIP Services

 

 

 

Additional SIP Services

 

Table 4-2 Additional SIP Services (continued)

 

 

 

 

 

 

 

 

 

SIP Service

Description

Reference

 

 

 

 

 

Proxy

The Cisco IP phone supports next hop server

See the “SIP Parameters”

 

Redundancy

redundancy when a fully qualified domain name

section on page 8-9.

 

support

(FQDN) is specified for the Proxy or Outbound Proxy

 

 

 

 

 

 

parameter. When sending a SIP request, the phone

 

 

 

 

 

 

performs a DNS SRV records query for the domain

 

 

 

 

 

 

name. The phone selects two records from the result

 

 

 

 

 

 

and identifies them as Primary Proxy Farm (PPF) and

 

 

 

 

 

 

Alternate Proxy Farm (APF). Each farm may contain

 

 

 

 

 

 

up to five IP addresses. If a DNS SRV record does not

 

 

 

 

 

 

exist, the phone performs a DNS A records query for

 

 

 

 

 

 

the domain name, which is now considered the Primary

 

 

 

 

 

 

Proxy Farm with no Alternate Proxy Farm. The phone

 

 

 

 

 

 

accepts up to five IP addresses from the query result.

 

 

 

 

 

 

The phone retries with the alternate next hop server for

 

 

 

 

 

 

the following SIP requests: REGISTER, INVITE,

 

 

 

 

 

 

CANCEL, BYE, REFER, and NOTIFY. If sending one

 

 

 

 

 

 

of these requests results in a 5xx response, no response,

 

 

 

 

 

 

or ARP timeout, the phone attempts the same request

 

 

 

 

 

 

with an alternate destination IP address derived from

 

 

 

 

 

 

the next hop domain name. If both primary and

 

 

 

 

 

 

alternate farms exist, the phone attempts the primary

 

 

 

 

 

 

farm first and then the alternate farm. The phone will

 

 

 

 

 

 

attempt all the IP addresses in one farm before

 

 

 

 

 

 

switching to the other farm. Once the phone finds a

 

 

 

 

 

 

responding next hop server, it remembers the farm and

 

 

 

 

 

 

IP address of the server and keeps using it for the given

 

 

 

 

 

 

domain name until it fails or expires. If the request still

 

 

 

 

 

 

fails after all the possible IP addresses are attempted,

 

 

 

 

 

 

the phone considers the request as failed.

 

 

 

 

 

 

If a server in the alternate proxy farm is active at the

 

 

 

 

 

 

moment, the phone can be configured to retry the

 

 

 

 

 

 

primary proxy farm after the number of seconds

 

 

 

 

 

 

specified by the AltProxyTimeout parameter. If this

 

 

 

 

 

 

value is 0, the phone remains with the alternate proxy

 

 

 

 

 

 

farm until all the IP addresses in the farm are down

 

 

 

 

 

 

before attempting the primary proxy farm again.

 

 

 

 

 

 

 

 

 

 

 

 

 

Cisco IP Phone Models 7905G and 7912G Administrator Guide (SIP)

 

 

 

 

 

 

 

OL-4277-01

 

 

 

4-9

 

 

 

 

 

Page 68 Page 70
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Image 69
Cisco Systems 7912G, 7905G manual Proxy Cisco IP phone supports next hop server
Page 68 Page 70

7912G, 7905G specifications

Cisco Systems is a leading provider of networking and telecommunications equipment, and among its extensive range of products, the Cisco 7900 Series of IP phones has made a notable impact in enterprise communication. Key models in this series include the Cisco 7905G, 7912G, and 7902G, each designed to enhance productivity through advanced features, intuitive interfaces, and robust technology.

The Cisco 7905G is designed for basic telephony needs and is ideal for administrative environments or areas with high call volumes. It features a large single-line LCD display, providing users with clear visibility of call information. The phone supports Power over Ethernet (PoE), making installation easier and reducing clutter by eliminating the need for an additional power supply. Its hands-free and headset support enhances user convenience, allowing for easy multitasking during calls.

Moving on to the Cisco 7912G, this model is designed for more demanding communication requirements. It features a larger, backlit display, providing improved visibility in various lighting conditions. The Cisco 7912G supports up to 12 programmable line or feature keys, giving users the flexibility to tailor the phone to their specific needs. Additionally, it incorporates advanced audio technologies, such as wideband audio for enhanced voice clarity and a built-in speakerphone, allowing users to communicate effectively in busy environments.

The Cisco 7902G, while offering basic features, is a reliable choice for users who need straightforward, cost-effective telephony solutions. It features an intuitive design with three dedicated buttons for line status, a built-in speakerphone, and support for wideband audio. The phone is geared for users who require essential telephony features without the complexity of additional functionalities, making it suitable for front-desk and general office use.

Overall, these models within the Cisco 7900 series exemplify the company's commitment to providing high-quality enterprise communication tools. With a focus on advanced audio technologies, user-friendly interfaces, and adaptability to various business environments, the Cisco 7905G, 7912G, and 7902G cater to the diverse needs of modern organizations. As companies continue to pursue seamless communication, these IP phones remain a valuable asset in their telephony infrastructure, enhancing collaboration and productivity among teams everywhere.
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