Actually it's one of the latest 1.2.0 revisions - b653c21. I didn't realize that with the quick look I had at the code. Curious. that makes me wonder if the Aastra phones are generating the noise when they don't see any media. A user complained about hearing the noise when first logging into voicemail, before she is asked for her PIN. I hadn't noticed it before because I normally do that on speaker but on the handset, it is quite noticeable. Is there a way to use send_silence_when_idle without having it kill ringback when set to a non-zero value? ---------- Anthony Minessale Thu May 17 20:21:35 MSD 2012 Which revision of the code are you looking at? The sleep sends dummy frames unless you set that send_silence_when_idle var, if its not set its probably not sending anything. You can see in the code that unless that var is set it wont be generating anything.