7925 phone on Alcatel WLAN roaming problem.

Unanswered Question
Aug 23rd, 2010
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Can anyone help me with the exact roaming values of a Cisco 7925 phone?
The phones are connected via a wlc from Alcatel.

The phones are changing ap’s constantly even staying on one spot.
Do to the roaming there are gaps in the call.

Now the Alcatel guys want to know on what values roaming happens.

I found this in the deployment guide but need more info

During a call, the Cisco Unified Wireless IP Phone 7925G measures Received Signal Strength Indicator (RSSI) and Packet Error Rate (PER)


The cell edge should be designed to -67 dBm where there is a 20-30% overlap of adjacent access points at that signal level.

This ensures the 7925G phone always has adequate signal and can roam seamlessly.

Channel Utilization

Channel Utilization levels should be kept under 50%.

If using the 7925G phone, this is provided via the QoS Basic Service Set (QBSS), which equates to around 105.


Noise levels should not exceed -92 dBm, which allows for a Signal to Noise Ratio (SNR) of 25 dB where a -67 dBm signal should be


Packet Loss / Delay

Per voice guidelines, packet loss should not exceed 1% packet loss, otherwise voice quality can be degraded significantly.

Jitter should be kept at a minimal (< 100 ms)


802.11 retransmissions should be less than 20%.


Multipath should be kept to a minimal as this can create nulls and reduce signal levels.


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