We are having issues with VoIP, using Microsoft Lync, over wireless. We are experiencing static, jitter, dead air, and dropped words during calls. We have a Cisco wireless infrastructure consisting of a 5508 controller and 2602 access points. We're currently runng OS version 7.5.102.0, but the issues also occurred when running OS version 7.4.100.0.
On the client side, we've narrowed the issues down to Dell Laptops(Latitude E6430, Latitude D640, Latitude E6420) with Dell Wireless/Broadcom(DW1530, DW1540) network adapters that are 802.11n capable.
Latitude E6430
OS - Windows 7
wireless adapter - DW1540
driver - 5.100.82.112
Latitude D640
OS - Windows 7
wireless adapter - DW1530
driver - 5.100.235.12
Latitude E6420
OS - Windows 8
wireless adapter - DW1530
driver - 6.30.58.26
All of the drivers are the latest offered from Dell.
If we disable high throughput (802.11n) on the access points and force the clients to connect with 802.11a or 802.11g, we don't experience any issues.
If we use another manufacturers 802.11n USB NIC in the same hardware, we don't experience any issues.
This seems to be a compatibility issue between Dell Wireless(Broadcom) 802.11n capable network adapters and Cisco access points. I'm guessing this issue is with all 802.11n traffic, but we're only noticing it during Microsoft Lync voice calls.
Has anybody else had this type of problem and found a resolution?
