diff --git a/src/server_cb.erl b/src/server_cb.erl
index 39976fc..c7b0ed1 100644
--- a/src/server_cb.erl
+++ b/src/server_cb.erl
@@ -180,7 +180,8 @@
 	NumUgran = req_num_of_vec(ReqUG),
 	lager:info("Num EUTRAN=~p, UTRAN=~p~n", [NumEutran, NumUgran]),
 	% construct GSUP request to HLR and transceive it
-	GsupTx1 = #{message_type => send_auth_info_req, imsi => list_to_binary(UserName)},
+	GsupTx1 = #{message_type => send_auth_info_req, imsi => list_to_binary(UserName),
+		    supported_rat_types => [rat_eutran_sgs], current_rat_type => rat_eutran_sgs},
 	case ReqEU of
 		#'Requested-EUTRAN-Authentication-Info'{'Re-Synchronization-Info' = ReSyncInfo}
 		when is_binary(ReSyncInfo) ->