sip-in hold/retr error handling: simply send BYE Because we know that the SIP state is CONNECTED at the time of any such error event, we can call initiate_bye() instead of disconnect_sip(), and thereby get rid of struct gsm_mncc_cause which will never be used in this scenario anyway.

/*
 * 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;
};