diff --git a/include/osmocom/gsm/Makefile.am b/include/osmocom/gsm/Makefile.am
index 3dbbad5..49a2ec4 100644
--- a/include/osmocom/gsm/Makefile.am
+++ b/include/osmocom/gsm/Makefile.am
@@ -1,7 +1,7 @@
 osmogsm_HEADERS = a5.h comp128.h gsm0808.h gsm48_ie.h mncc.h rxlev_stat.h \
 		  gsm0480.h gsm48.h gsm_utils.h rsl.h tlv.h abis_nm.h \
 		  sysinfo.h prim.h gsm0502.h lapd_core.h lapdm.h \
-		  gsm0411_utils.h
+		  gsm0411_utils.h gsm0411_smc.h
 
 SUBDIRS = protocol
 
diff --git a/include/osmocom/gsm/gsm0411_smc.h b/include/osmocom/gsm/gsm0411_smc.h
new file mode 100644
index 0000000..e1508a2
--- /dev/null
+++ b/include/osmocom/gsm/gsm0411_smc.h
@@ -0,0 +1,62 @@
+#ifndef _GSM0411_SMC_H
+#define _GSM0411_SMC_H
+
+#include <osmocom/gsm/protocol/gsm_04_11.h>
+
+#define GSM411_MMSMS_EST_REQ		0x310
+#define GSM411_MMSMS_EST_IND		0x312
+#define GSM411_MMSMS_EST_CNF		0x311
+#define GSM411_MMSMS_REL_REQ		0x320
+#define GSM411_MMSMS_REL_IND		0x322
+#define GSM411_MMSMS_DATA_REQ		0x330
+#define GSM411_MMSMS_DATA_IND		0x332
+#define GSM411_MMSMS_UNIT_DATA_REQ	0x340
+#define GSM411_MMSMS_UNIT_DATA_IND	0x342
+#define GSM411_MMSMS_ERR_IND		0x372
+
+#define GSM411_MNSMS_ABORT_REQ		0x101
+#define GSM411_MNSMS_DATA_REQ		0x102
+#define GSM411_MNSMS_DATA_IND		0x103
+#define GSM411_MNSMS_EST_REQ		0x104
+#define GSM411_MNSMS_EST_IND		0x105
+#define GSM411_MNSMS_ERROR_IND		0x106
+#define GSM411_MNSMS_REL_REQ		0x107
+
+struct gsm411_smc_inst {
+	int network;		/* is this a MO (0) or MT (1) transfer */
+	int (*mn_recv) (struct gsm411_smc_inst *inst, int msg_type,
+			struct msgb *msg);
+	int (*mm_send) (struct gsm411_smc_inst *inst, int msg_type,
+			struct msgb *msg, int cp_msg_type);
+
+	enum gsm411_cp_state cp_state;
+	struct osmo_timer_list cp_timer;
+	struct msgb *cp_msg;	/* store pending message */
+	int cp_rel;		/* store pending release */
+	int cp_retx;		/* retry counter */
+	int cp_max_retr;	/* maximum retry */
+	int cp_tc1;		/* timer value TC1* */
+
+};
+
+extern const struct value_string gsm411_cp_cause_strs[];
+
+/* init a new instance */
+void gsm411_smc_init(struct gsm411_smc_inst *inst, int network,
+	int (*mn_recv) (struct gsm411_smc_inst *inst, int msg_type,
+			struct msgb *msg),
+	int (*mm_send) (struct gsm411_smc_inst *inst, int msg_type,
+			struct msgb *msg, int cp_msg_type));
+
+/* clear instance */
+void gsm411_smc_clear(struct gsm411_smc_inst *inst);
+
+/* message from upper layer */
+int gsm411_smc_send(struct gsm411_smc_inst *inst, int msg_type,
+	struct msgb *msg);
+
+/* message from lower layer */
+int gsm411_smc_recv(struct gsm411_smc_inst *inst, int msg_type,
+	struct msgb *msg, int cp_msg_type);
+
+#endif /* _GSM0411_SMC_H */
diff --git a/include/osmocom/gsm/protocol/gsm_04_11.h b/include/osmocom/gsm/protocol/gsm_04_11.h
index c6a2b19..905ea9c 100644
--- a/include/osmocom/gsm/protocol/gsm_04_11.h
+++ b/include/osmocom/gsm/protocol/gsm_04_11.h
@@ -5,7 +5,7 @@
 
 /* GSM TS 04.11  definitions */
 
-/* Chapter 5.2.3: SMC-CS states at the network side */
+/* Chapter 5.2.3: SMC-CS states at the user/network side */
 enum gsm411_cp_state {
 	GSM411_CPS_IDLE 		= 0,
 	GSM411_CPS_MM_CONN_PENDING	= 1,	/* only MT ! */
@@ -13,11 +13,12 @@
 	GSM411_CPS_MM_ESTABLISHED	= 3,
 };
 
-/* Chapter 6.2.2: SMR states at the network side */
+/* Chapter 6.2.2: SMR states at the user/network side */
 enum gsm411_rp_state {
 	GSM411_RPS_IDLE			= 0,
 	GSM411_RPS_WAIT_FOR_RP_ACK	= 1,
 	GSM411_RPS_WAIT_TO_TX_RP_ACK	= 3,
+	GSM411_RPS_WAIT_FOR_RETRANS_T	= 4,
 };
 
 /* Chapter 8.1.2 (refers to GSM 04.07 Chapter 11.2.3.1.1 */
@@ -95,7 +96,7 @@
 #define GSM411_TMR_TRAM		30, 0	/* 25 < x < 35 seconds */
 #define GSM411_TMR_TR2M		15, 0	/* 12 < x < 20 seconds */
 
-#define GSM411_TMR_TC1A		30, 0
+#define GSM411_TMR_TC1A		30	/* TR1M - 10 */
 
 /* Chapter 8.2.1 */
 struct gsm411_rp_hdr {