diff --git a/src/modules/network_element/service/udm_auth.impl.go b/src/modules/network_element/service/udm_auth.impl.go
index ed7cc4ab..75a051a1 100644
--- a/src/modules/network_element/service/udm_auth.impl.go
+++ b/src/modules/network_element/service/udm_auth.impl.go
@@ -113,6 +113,9 @@ func (r *UDMAuthImpl) InsertCSV(neID string, data []map[string]string) int64 {
 	prefixes := make(map[string]struct{})
 	for _, v := range data {
 		imsi := v["imsi"]
+		if len(imsi) < 5 {
+			continue
+		}
 		prefix := imsi[:len(imsi)-4]
 		prefixes[prefix] = struct{}{}
 	}
@@ -133,6 +136,9 @@ func (r *UDMAuthImpl) InsertTxt(neID string, data [][]string) int64 {
 	prefixes := make(map[string]struct{})
 	for _, v := range data {
 		imsi := v[0]
+		if len(imsi) < 5 {
+			continue
+		}
 		prefix := imsi[:len(imsi)-4]
 		prefixes[prefix] = struct{}{}
 	}
diff --git a/src/modules/network_element/service/udm_sub.impl.go b/src/modules/network_element/service/udm_sub.impl.go
index 617a0a39..45fc5cd4 100644
--- a/src/modules/network_element/service/udm_sub.impl.go
+++ b/src/modules/network_element/service/udm_sub.impl.go
@@ -129,6 +129,9 @@ func (r *UDMSubImpl) InsertCSV(neID string, data []map[string]string) int64 {
 	prefixes := make(map[string]struct{})
 	for _, v := range data {
 		imsi := v["imsi"]
+		if len(imsi) < 5 {
+			continue
+		}
 		prefix := imsi[:len(imsi)-4]
 		prefixes[prefix] = struct{}{}
 	}
@@ -149,6 +152,9 @@ func (r *UDMSubImpl) InsertTxt(neID string, data [][]string) int64 {
 	prefixes := make(map[string]struct{})
 	for _, v := range data {
 		imsi := v[0]
+		if len(imsi) < 5 {
+			continue
+		}
 		prefix := imsi[:len(imsi)-4]
 		prefixes[prefix] = struct{}{}
 	}