Buzzing on GSM audio

Joerg Reisenweber joerg at
Sat Jul 26 14:11:27 CEST 2008

Am Sa  26. Juli 2008 schrieb rakshat hooja:
> I have an interesting observation to share. India still has old fixed copper
> wire telephones (landlines) and when I call a landlines both sides seem to
> be getting clear connections (no buzz and even the volume on the receivers
> end is louder)
> When calling a GSM mobile there is a buzz (sometimes, not always when I call
> someone using my provider [Airtel in India] and almost always when calling
> someone on another provider). Even more interestingly some people have
> claimed that the volume and buzz is less when they call me. For example many
> times I call someone, they will say that there is disturbance and that they
> are going to cut the call and call me back. And when they call back they
> report a clearer line.
> I am using the latest Qtopia kernel and Rootfs.
> Anyway I have started to use the Freerunner as my only phone so I will be
> automatically testing the GSM buzz problem on each call!
> Another approach I was thinking of was that if there is anyone on the list
> who is not having the GSM buzz problem to please write in with their kernel,
> rootfs and provider information.

The research on this topic so far seems to suggest this is a mere 
RF-feedback_to_audiopath issue. Thus I can't see how the type of far end or 
in/out-direction of call is going to change anything on buzz-noise.
But, as I stated repeatedly, this is a very random effect, and it's not yet 
completely understood which factors are of any influence. So for sure we may 
benefit from your constant testing. However please be an alert observer, 
don't move to the outside between end of call and your far end calling back, 
example given. Also please don't conclude from a small number of samples, 
there's too much random spoiling the results.

Thanks for the report, please keep us informed! :-)
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