Hi, every now and then it happens if there is no data on the mic input port. In this case it will generate a frame to keep in sync. In this case the message is ok and harmless. Especially for USB audio devices, even worse on a computers with poor performance or some kind of processor speed stepping, I have seen the same behaviour. On good systems even, it sometimes occurs after some weeks of operation. In this case the PJSUA is always ahead of windows and never seems to get a right audio packet. I tried everything but I have no answer up to now. I upgraded portaudio to the latest stable version and had some limited succes in opening and closing all sound devices. The latter worked, but is very unhandy and does not cover all circumstances. Is there someone else experiencing this problem? Cheers, Andreas Am 23.01.2013 11:46, schrieb Kresten Tolstrup: > Hi > > I have an application running on windows 7, pjsip version 1.10, and > sometimes the application is writting > "Master/sound underflow, buf_cnt=0, will generate one frame" > > the line is written very fast, and all the time, and no audio is sent. > The application is never getting out of that mode, unless it is closed > and restartet. > > What can I do to prevent the application to get into that mode ?