Chapter 1 Overview

Recommendations for Successful VoIP Surveys

The characteristics of VoIP require a meticulous WIPT site survey. To avoid a call with jitter, the delay variation between packets should not exceed 30 ms. The one-way delay should not exceed 150 ms and packet loss should not exceed one percent. Surveying for a one percent packet loss is important because VoIP uses the Real-Time Transport Protocol (RTP), which does not retransmit for lost packets. Voice packets are small but are sent at consistent intervals. The 7920 client assumes that it has lost its connection to an access point if it misses 3 consecutive beacons. The access point sends a beacon every 100 ms, which means that the Cisco 7920 looks for another access point if it does not see beacons every 300 ms from the access point to which it is associated.

Multi-floor survey

At many sites it is important to consider the effect of above-floor and below-floor coverage. An antenna placed near a ceiling in a multi-floor facility can easily provide coverage to the floor above. There will be considerable loss in dBm signal strength, but the signal can still have enough quality to be usable.

Depending on the capacity, throughput, and coverage requirement for the site, the power of the access point may be turned down to minimize the signal coverage between floors. An Omni antenna propagates directly above it into the floor above. A patch antenna will also propagate signal into the floor above, but not directly above as the Omni antenna will. Although directional antennas help focus the signal energy in a particular direction, which can help to overcome fading and multipath signals, multipath signals reduce the focused power of a directional antenna and the amount of multipath seen by a user at a long distance from the access point can be much greater. Directional antennas used indoors typically are low gain (5 dBi to 10 dBi), and therefore have lower front-to-back and front-to-side lobe ratios. This reduces the radio’s ability to reject or reduce the interference signals received from directions outside the primary lobe area. A low-gain directional antenna, such as a 6.5-dBi patch, will receive signal from the sides and the back, but the primary coverage area will be forward. The coverage in Figure 1-5represents an Omni antenna coverage. The cell coverage overlap and same-channel separation should be maintained at a multi-floor site.

Figure 1-5 Survey in a Building with Multiple Floors

Different types of facilities, such as hospitals and schools, have different signal propagation patterns, multipath levels, and attenuation levels.

Site Survey Guide for Deploying Cisco 7920 IP Phones

 

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Cisco Systems 7920 manual Multi-floor survey, Survey in a Building with Multiple Floors
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7920 specifications

Cisco Systems, a leading player in the global networking and communications technology sector, designed the Cisco 7920 Wireless IP Phone for mobile professionals seeking seamless connectivity in various environments. Primarily aimed at enhancing communication within enterprise settings, this wireless device offers a plethora of features that cater to the specific needs of businesses.

At the core of the Cisco 7920 is its robust wireless functionality. It operates on IEEE 802.11b/g wireless protocols, allowing users to connect effortlessly to Wi-Fi networks. This flexibility enables employees to communicate effectively from various locations within an office space, promoting mobility and collaboration without being tethered to a desk.

The ergonomic design of the Cisco 7920 prioritizes user comfort. Its lightweight casing and intuitive button layout ensure that users can navigate the interface with ease. The device is equipped with a vibrant color display, allowing for clear visibility of caller ID, call status, and menu options, enhancing the user experience further. Additionally, the handset supports a wide variety of languages, making it suitable for global teams.

In terms of features, the Cisco 7920 is loaded with advanced capabilities. It supports voice over IP (VoIP), delivering high-quality audio and ensuring reliable communication. Users benefit from features like a contextual menu, call hold, transfer, conference calling, and voicemail access on the go. The phone also offers a wide range of ringtones, allowing customization to suit personal preferences or company branding.

Security is a crucial aspect of modern telecommunications, and the Cisco 7920 does not fall short. It incorporates industry-standard security protocols such as Wired Equivalent Privacy (WEP) and Wi-Fi Protected Access (WPA), safeguarding communications from potential threats.

Moreover, the Cisco 7920 integrates seamlessly with Cisco Unified Communications Manager, enabling centralized management and control. This integration ensures that IT departments can deploy, manage, and troubleshoot devices efficiently, streamlining operations while ensuring optimal performance.

In conclusion, the Cisco 7920 Wireless IP Phone stands out as a versatile communication tool designed for the fast-paced workplace. Its combination of wireless connectivity, ergonomic design, advanced features, and robust security makes it an essential accessory for businesses looking to elevate their communication strategies. With its established reputation, Cisco continues to support companies in achieving seamless connectivity and effective collaboration.
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