sgsn: add testcases for SGSN Context Request procedure

Change-Id: If71de10897a8a9f6612cd46c760cd89c0299ac2c
Related: SYS#6603, OS#6294
diff --git a/library/GTPv1C_Templates.ttcn b/library/GTPv1C_Templates.ttcn
index e9cf797..0907c5e 100644
--- a/library/GTPv1C_Templates.ttcn
+++ b/library/GTPv1C_Templates.ttcn
@@ -67,7 +67,8 @@
 		GTP_CAUSE_MS_REFUSES			(4),
 		GTP_CAUSE_MS_IS_NOT_GPRS_RESPONDING	(5),
 		/* reserved */
-		GTP_CAUSE_REQUEST_ACCEPTED		(128)
+		GTP_CAUSE_REQUEST_ACCEPTED		(128),
+		GTP_CAUSE_INVALID_MSG_FORMAT		(193)
 		/* FIXME */
 	};