It's been a long time since I worked with named pipes, but if memory serves me a reader of a pipe will get an EOF (end-of-file) for any read if there is no writer attached, which would prevent the phone application from getting any data if it tries to read before the dbus notification has propagated to us. If that's the case, we'll need to have the perl script open the pipe for writing (and keep it open all the time), and simply funnel pcm data into it from mplayer when needed.