diff --git a/libpri.h b/libpri.h
index afbb029..89dbb2a 100644
--- a/libpri.h
+++ b/libpri.h
@@ -915,6 +915,17 @@ int pri_redirecting_update(struct pri *pri, q931_call *call, const struct pri_pa
 #define PRI_HANGUP
 int pri_hangup(struct pri *pri, q931_call *call, int cause);
 
+/*!
+ * \brief Set the call hangup fix enable flag.
+ *
+ * \param ctrl D channel controller.
+ * \param enable TRUE to follow Q.931 Section 5.3.2 call hangup better.
+ * FALSE for legacy behaviour. (Default FALSE if not called.)
+ *
+ * \return Nothing
+ */
+void pri_hangup_fix_enable(struct pri *ctrl, int enable);
+
 #define PRI_DESTROYCALL
 void pri_destroycall(struct pri *pri, q931_call *call);
 
diff --git a/pri.c b/pri.c
index 80a7b2b..4aa9456 100644
--- a/pri.c
+++ b/pri.c
@@ -965,6 +965,14 @@ int pri_channel_bridge(q931_call *call1, q931_call *call2)
 	}
 }
 
+void pri_hangup_fix_enable(struct pri *ctrl, int enable)
+{
+	if (ctrl) {
+		ctrl = PRI_MASTER(ctrl);
+		ctrl->hangup_fix_enabled = enable ? 1 : 0;
+	}
+}
+
 int pri_hangup(struct pri *pri, q931_call *call, int cause)
 {
 	if (!pri || !call)
diff --git a/pri_internal.h b/pri_internal.h
index eb49577..edb8bb6 100644
--- a/pri_internal.h
+++ b/pri_internal.h
@@ -92,6 +92,7 @@ struct pri {
 	unsigned int service_message_support:1;/* TRUE if upper layer supports SERVICE messages */
 	unsigned int hold_support:1;/* TRUE if upper layer supports call hold. */
 	unsigned int deflection_support:1;/* TRUE if upper layer supports call deflection/rerouting. */
+	unsigned int hangup_fix_enabled:1;/* TRUE if should follow Q.931 Section 5.3.2 instead of blindly sending RELEASE_COMPLETE for certain causes */
 
 	/* MDL variables */
 	int mdl_error;
diff --git a/q931.c b/q931.c
index d1b0325..867e373 100644
--- a/q931.c
+++ b/q931.c
@@ -5397,6 +5397,12 @@ static int __q931_hangup(struct pri *ctrl, q931_call *c, int cause)
 	case PRI_CAUSE_REQUESTED_CHAN_UNAVAIL:
 	case PRI_CAUSE_IDENTIFIED_CHANNEL_NOTEXIST:
 	case PRI_CAUSE_UNALLOCATED:
+		if (!PRI_MASTER(ctrl)->hangup_fix_enabled) {
+			/* Legacy: We'll send RELEASE_COMPLETE with these causes */
+			disconnect = 0;
+			release_compl = 1;
+			break;
+		}
 		/* See Q.931 Section 5.3.2 a) */
 		switch (c->ourcallstate) {
 		case Q931_CALL_STATE_NULL: