diff --git a/src/libcommon/gsm_data.c b/src/libcommon/gsm_data.c
index db7de08..7c717a4 100644
--- a/src/libcommon/gsm_data.c
+++ b/src/libcommon/gsm_data.c
@@ -471,3 +471,13 @@
 		cell_options->radio_link_timeout = (value >> 2) - 1;
 	}
 }
+
+bool classmark_is_r99(struct gsm_classmark *cm)
+{
+	int rev_lev = 0;
+	if (cm->classmark1_set)
+		rev_lev = cm->classmark1.rev_lev;
+	else if (cm->classmark2_len > 0)
+		rev_lev = (cm->classmark2[0] >> 5) & 0x3;
+	return rev_lev >= 2;
+}