Hello to all. My linphone can't respond to a NOTIFY message. IT's connected to an Asterisk, and when it sends me a notify, my system responds with a 501 message error. Why can I do to support notify? I have some problems with the refer service, due to the protocol sends me a notify and I respond with 501 instead 200 OK, and for some motive Asterisk send me a notify periodically,too.