diff --git a/openbsc/include/openbsc/gsm_data.h b/openbsc/include/openbsc/gsm_data.h
index c547cd7..9e808fc 100644
--- a/openbsc/include/openbsc/gsm_data.h
+++ b/openbsc/include/openbsc/gsm_data.h
@@ -215,6 +215,7 @@
 };
 
 #define GSM_T3101_DEFAULT 10
+#define GSM_T3105_DEFAULT 40
 #define GSM_T3113_DEFAULT 60
 
 struct gsm_network {