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FAQ - Cisco Unified Communications 500 Series - Cisco Smart Business Communication Systems


Q: I have a customer with UC500 with an integrated access point complaining of low throughput

A: A UC520 with an integrated AP can be used in order to provide WiFi coverage if the desired service area is within the vicinity of the physical UC520 unit. This option is optimal for a small office environment that installs the UC520 as a desktop unit. As is the practise with any wireless installation, please ensure that the customer has performed a complete site survey.

Another option would be to move the unit to a better location and perhaps have it wall mounted such that the antenna is visible/exposed - rather than a location where it potentially could be blocked by metal racks/etc.

Q: Customer has 3 Cisco 7921 phones that are registered to the integrated Access Point and is complaining about choppy voice quality.

A: The integrated Access Point on the UC500 was primarily designed for "data" centric applications. Even though the integrated access point supports voice over wireless, for optimal performance and a higher requirment for of voice over wireless LAN (VoWLAN) clients, like the Cisco 7921 IP Phones, we recommend that the customer go with the Cisco AP521G Autonomous Access Point or the Cisco Mobility Express solution with the LWAPP based AP521 and WLAN Controller 526.

In the interim there are a couple of workarounds that could mitigate the issue:

1. Ensure that power save mode is disabled on the Cisco 7921 phones

Settings -> Network Profiles -> Profile Number -> WLAN configuration ->Call Power Save Mode (press **#) and change it to NONE

2. Please make the following changes on the UC520 using the CLI

UC520#conf t

Enter configuration commands, one per line. End with CNTL/Z.

UC520(config)#ephone-dn 9

UC520(config-ephone-dn)#no moh ip port 2139 out-call ABC

UC520(config-ephone-dn)#moh out-call ABC




Default Config:

ephone-dn  9

number BCD no-reg primary

description MoH

moh ip port 2139 out-call ABC

After change

ephone-dn  9

number BCD no-reg primary

description MoH

moh out-call ABC

Q: What are the guidelines for how many wireless access points are needed?

A: Here is a guideline:

Refining the estimateWireless2.JPG

For RRM to work effectively at least 3 APs are required

For Fast Secure Roaming and seamless Mobility of the Wireless VoIP phones WLC has to be deployed.


Optimal radio planning takes radio expertise, site surveys and experience.  Cisco offers training courses. The SBCS/Mobility Express makes radio planning a little bit easier with one type of antenna (omni-directional)and 802.11 b/g RF. The controller’s RRM feature will adjust channels and power settings in real time to constantly optimize.

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