I would like to create an ermergency call application : if triggered, it calls a given number and play an audio file, giving the information the caller couldn't give himself.
For that I need to engage a call but ensure that I can replace any sound from the speaker with an played audio file. Can I do that in android ? What's the way ?
You can't do this with the G1 at this time, because two different processors handle the call and the apps, and there is no path between them. AFAIK this isn't in the SDK yet, but assuming hardware comes out that can do it, it will be added to the SDK.
http://groups.google.com/group/android-developers/browse_thread/thread/d04c307973345fef/a628e578900b3dce?lnk=gst&q=dave+sparks+play+audio#a628e578900b3dce