mgw: accept zero-length RTP payload as BFI Mainline OsmoBTS now has an option (rtp continuous-streaming) that causes it to emit an RTP packet every 20 ms without gaps, sending a BFI marker in the form of zero-length RTP payload when it has nothing else to send. These codec-independent BFI markers don't indicate TAF, but this provision is a good start. Accept this BFI packet format in themwi-mgw.

/*
 * Here we define the structure we are going to use for constructing
 * outgoing SIP messages (UDP packets).
 */

#define	MAX_SIP_TX_PACKET	1472

struct sip_msg_out {
	char		buf[MAX_SIP_TX_PACKET];
	unsigned	msg_len;
};