We've been having an issue for several months now with our over 200 7925g phones. Nurses are complaining that the phones have static and will drop the voice of the other caller and several times need to repeat the conversation. We have confirmed several scenario's. It occurs when both callers are on 7925g inside the coverage areas in the hospital; between 7925g and 7940 desk phone; 7925g and Nortel desk phone. We've tested on 802.11a and 802.11b/g. I do see a difference when on 802.11b/g however still get a hissing when connecting to a different AP.
4 - 4400 controllers, 6.0.202 firmware
1 - 5508 controller, 6.0.202 firmware
234 - LAP1131AG AP's
6 - AP1131AG AP's
7 - LAP1142N AP's
3 - LAP1310G AP's
AP's are on 220.127.116.11 firmware
7925g's all are on 1.3.3 firmware but we have a select few that we are testing at both hospitals with the newest firmware 1.4.1 and still same results.
235 - 7925g phones.
We have followed the 7925g setup & deployment guide, WLC Config Analyzer and made sure all checks were made. The only setting we plan on testing this week is changing the CCKM authentication change which was recommended. Currently we are WPA TKIP
We have disabled the higher rates (36-54) on the 802.11a.
We also have AirMagnet VoFi analyzer which is showing issues when roaming from AP. The alarms indicate a one-way audio issue and points to the AP's and phones power not matching. We have our Tx power level on the controller to automatic, Max Power Level at 30 dBm, Min. at -10 dBm, power Threshold at -70 (WLC Config Analyzer recommendation). The phone TX Power is set at 8 dBm. Call Power Save Mode has been tested with both None and U-APDS/PS-Poll.
We have a case open with Cisco TAC and she has requested debugs from our controllers. I have sent over 7 and she is not coming back with anything solid and not much help so far.
Our tests between 802.11a and 802.11b/g (RSSI setting on phone Auto-a and Auto-bg) have shown better with the bg mode but still static and/or hissing.
Any help would be greatly appreciated! Thanks.
Yeah I spoke to the TAC engineer that just picked up the case yesterday about next steps.
Would recommend 18.104.22.168.1.7 / 1.4(2) for any highly mobile environment (e.g. Healthcare).
FYI, 1.4(2) is due out at the end of the year.
Glad it is working out for you so far.
All of these settings sound good and what I have outlined in the 7925G Deployment Guide.
Definitely want to enable CCKM if using 802.1x.
Continuous scan mode can help with location as the phone is scanning all the time regardless of call state.
There is a small hit on battery life with continuous scan mode, but will not be significant to impact day to day operations.
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