diff --git a/library/GSUP_Types.ttcn b/library/GSUP_Types.ttcn
index 4c2aac0..359e272 100644
--- a/library/GSUP_Types.ttcn
+++ b/library/GSUP_Types.ttcn
@@ -39,7 +39,11 @@
 	OSMO_GSUP_AUTN_IE		('25'O),
 	OSMO_GSUP_AUTS_IE		('26'O),
 	OSMO_GSUP_RES_IE		('27'O),
-	OSMO_GSUP_CN_DOMAIN_IE		('28'O)
+	OSMO_GSUP_CN_DOMAIN_IE		('28'O),
+
+	OSMO_GSUP_SESSION_ID_IE		('30'O),
+	OSMO_GSUP_SESSION_STATE_IE	('31'O),
+	OSMO_GSUP_SS_INFO_IE		('35'O)
 } with { variant "FIELDLENGTH(8)" };
 
 type enumerated GSUP_MessageType {
@@ -67,7 +71,11 @@
 
 	OSMO_GSUP_MSGT_LOCATION_CANCEL_REQUEST	('00011100'B),
 	OSMO_GSUP_MSGT_LOCATION_CANCEL_ERROR	('00011101'B),
-	OSMO_GSUP_MSGT_LOCATION_CANCEL_RESULT	('00011110'B)
+	OSMO_GSUP_MSGT_LOCATION_CANCEL_RESULT	('00011110'B),
+
+	OSMO_GSUP_MSGT_PROC_SS_REQUEST		('00100000'B),
+	OSMO_GSUP_MSGT_PROC_SS_ERROR		('00100001'B),
+	OSMO_GSUP_MSGT_PROC_SS_RESULT		('00100010'B)
 } with { variant "FIELDLENGTH(8)" };
 
 type enumerated GSUP_CancelType {
@@ -80,6 +88,13 @@
 	OSMO_GSUP_CN_DOMAIN_CS			(2)
 } with { variant "FIELDLENGTH(8)" };
 
+type enumerated GSUP_SessionState {
+	OSMO_GSUP_SESSION_STATE_NONE		(0),
+	OSMO_GSUP_SESSION_STATE_BEGIN		(1),
+	OSMO_GSUP_SESSION_STATE_CONTINUE	(2),
+	OSMO_GSUP_SESSION_STATE_END		(3)
+} with { variant "FIELDLENGTH(8)" };
+
 type record GSUP_MSISDN {
 	uint8_t	len,
 	hexstring digits optional
@@ -110,6 +125,9 @@
 				 pdp_qos, tag = OSMO_GSUP_PDP_QOS_IE;
 				 pdp_type, tag = OSMO_GSUP_PDP_TYPE_IE;
 				 charg_char, tag = OSMO_GSUP_CHARG_CHAR_IE;
+				 session_state, tag = OSMO_GSUP_SESSION_STATE_IE;
+				 session_id, tag = OSMO_GSUP_SESSION_ID_IE;
+				 ss_info, tag = OSMO_GSUP_SS_INFO_IE;
 			)"
 };
 
@@ -138,7 +156,12 @@
 	octetstring	apn,
 	octetstring	pdp_qos,
 	OCT2		pdp_type,
-	octetstring	charg_char
+	octetstring	charg_char,
+	/* Session information */
+	GSUP_SessionState	session_state,
+	OCT4			session_id,
+	/* Supplementary Services */
+	octetstring		ss_info
 };
 
 type record GSUP_PDU {
@@ -513,5 +536,132 @@
 	}
 }
 
+template (value) GSUP_IE ts_GSUP_IE_SessionId(OCT4 sid) := {
+	tag := OSMO_GSUP_SESSION_ID_IE,
+	len := 0, /* overwritten */
+	val := {
+		session_id := sid
+	}
+}
+template GSUP_IE tr_GSUP_IE_SessionId(template OCT4 sid) := {
+	tag := OSMO_GSUP_SESSION_ID_IE,
+	len := ?,
+	val := {
+		session_id := sid
+	}
+}
+
+template (value) GSUP_IE ts_GSUP_IE_SessionState(GSUP_SessionState state) := {
+	tag := OSMO_GSUP_SESSION_STATE_IE,
+	len := 0, /* overwritten */
+	val := {
+		session_state := state
+	}
+}
+template GSUP_IE tr_GSUP_IE_SessionState(template GSUP_SessionState state) := {
+	tag := OSMO_GSUP_SESSION_STATE_IE,
+	len := ?,
+	val := {
+		session_state := state
+	}
+}
+
+template (value) GSUP_IE ts_GSUP_IE_SSInfo(octetstring ss) := {
+	tag := OSMO_GSUP_SS_INFO_IE,
+	len := 0, /* overwritten */
+	val := {
+		ss_info := ss
+	}
+}
+template GSUP_IE tr_GSUP_IE_SSInfo(template octetstring ss) := {
+	tag := OSMO_GSUP_SS_INFO_IE,
+	len := ?,
+	val := {
+		ss_info := ss
+	}
+}
+
+template (value) GSUP_PDU ts_GSUP_PROC_SS_REQ(
+	hexstring imsi,
+	OCT4 sid,
+	GSUP_SessionState state,
+	octetstring ss
+) := ts_GSUP(
+	OSMO_GSUP_MSGT_PROC_SS_REQUEST,
+	{
+		valueof(ts_GSUP_IE_IMSI(imsi)),
+		valueof(ts_GSUP_IE_SessionId(sid)),
+		valueof(ts_GSUP_IE_SessionState(state)),
+		valueof(ts_GSUP_IE_SSInfo(ss))
+	}
+);
+template GSUP_PDU tr_GSUP_PROC_SS_REQ(
+	template hexstring imsi,
+	template OCT4 sid := ?,
+	template GSUP_SessionState state := ?,
+	template octetstring ss := ?
+) := tr_GSUP(
+	OSMO_GSUP_MSGT_PROC_SS_REQUEST,
+	{
+		tr_GSUP_IE_IMSI(imsi),
+		tr_GSUP_IE_SessionId(sid),
+		tr_GSUP_IE_SessionState(state),
+		tr_GSUP_IE_SSInfo(ss)
+	}
+);
+
+template (value) GSUP_PDU ts_GSUP_PROC_SS_RES(
+	hexstring imsi,
+	OCT4 sid,
+	GSUP_SessionState state,
+	octetstring ss
+) := ts_GSUP(
+	OSMO_GSUP_MSGT_PROC_SS_RESULT,
+	{
+		valueof(ts_GSUP_IE_IMSI(imsi)),
+		valueof(ts_GSUP_IE_SessionId(sid)),
+		valueof(ts_GSUP_IE_SessionState(state)),
+		valueof(ts_GSUP_IE_SSInfo(ss))
+	}
+);
+template GSUP_PDU tr_GSUP_PROC_SS_RES(
+	template hexstring imsi,
+	template OCT4 sid := ?,
+	template GSUP_SessionState state := ?,
+	template octetstring ss := ?
+) := tr_GSUP(
+	OSMO_GSUP_MSGT_PROC_SS_RESULT,
+	{
+		tr_GSUP_IE_IMSI(imsi),
+		tr_GSUP_IE_SessionId(sid),
+		tr_GSUP_IE_SessionState(state),
+		tr_GSUP_IE_SSInfo(ss)
+	}
+);
+
+template (value) GSUP_PDU ts_GSUP_PROC_SS_ERR(
+	hexstring imsi,
+	OCT4 sid,
+	integer cause
+) := ts_GSUP(
+	OSMO_GSUP_MSGT_PROC_SS_ERROR,
+	{
+		valueof(ts_GSUP_IE_IMSI(imsi)),
+		valueof(ts_GSUP_IE_SessionId(sid)),
+		valueof(ts_GSUP_IE_Cause(cause))
+	}
+);
+template GSUP_PDU tr_GSUP_PROC_SS_ERR(
+	template hexstring imsi,
+	template OCT4 sid := ?,
+	template integer cause := ?
+) := tr_GSUP(
+	OSMO_GSUP_MSGT_PROC_SS_ERROR,
+	{
+		tr_GSUP_IE_IMSI(imsi),
+		tr_GSUP_IE_SessionId(sid),
+		tr_GSUP_IE_Cause(cause)
+	}
+);
 
 } with { encode "RAW"; variant "FIELDORDER(msb)" }