I deployed a UC540 and about 10 SPA505G's. For some reason all of the SPA504G's have a slight digitized noise periodically. I gave a few users some 7941's to try out and they said it's crystal clear.
I've used the SPA504G's with non Cisco deployments and they work perfectly.
Has anyone else noticed this? FYI. I have updated all phones and UC to latest software.