We have a new deployment where we have 5 total 7921G wifi phones connected via 2 AP541n access points, one connected to a ESW520p switch and then to the UC540 and the other connected directly to the UC540. The wifi phones are intermittently giving no audio when calling each other, however, calls to the PSTN consistently do have 2 way audio. Is this a security issue perhaps? We are running the latest CCA software pack as this is a brand new deployment, also the AP's were upgraded to the latest firmware. HELP.