diff --git a/openbsc/include/openbsc/mgcp.h b/openbsc/include/openbsc/mgcp.h
index 38fe50482..02abeea39 100644
--- a/openbsc/include/openbsc/mgcp.h
+++ b/openbsc/include/openbsc/mgcp.h
@@ -147,7 +147,7 @@ static inline int mgcp_timeslot_to_endpoint(int multiplex, int timeslot)
 {
 	if (timeslot == 0)
 		timeslot = 1;
-	return timeslot + (31 * multiplex);
+	return timeslot + (32 * multiplex);
 }