diff --git a/src/libosmo-mgcp/mgcp_protocol.c b/src/libosmo-mgcp/mgcp_protocol.c
index 1e393e2..f2fc20c 100644
--- a/src/libosmo-mgcp/mgcp_protocol.c
+++ b/src/libosmo-mgcp/mgcp_protocol.c
@@ -747,6 +747,10 @@
 	int rc;
 
 	LOGPENDP(endp, DLMGCP, LOGL_NOTICE, "CRCX: creating new connection ...\n");
+	if (!mgcp_endp_avail(endp)) {
+		rate_ctr_inc(&rate_ctrs->ctr[MGCP_CRCX_FAIL_AVAIL]);
+		return create_err_response(NULL, 501, "CRCX", p->trans);
+	}
 
 	/* parse CallID C: and LocalParameters L: */
 	for_each_line(line, p->save) {
@@ -1004,6 +1008,11 @@
 
 	LOGPENDP(endp, DLMGCP, LOGL_NOTICE, "MDCX: modifying existing connection ...\n");
 
+	if (!mgcp_endp_avail(endp)) {
+		rate_ctr_inc(&rate_ctrs->ctr[MGCP_MDCX_FAIL_AVAIL]);
+		return create_err_response(NULL, 501, "MDCX", p->trans);
+	}
+
 	/* Prohibit wildcarded requests */
 	if (endp->wildcarded_req) {
 		LOGPENDP(endp, DLMGCP, LOGL_ERROR,
@@ -1224,6 +1233,11 @@
 	LOGPENDP(endp, DLMGCP, LOGL_NOTICE,
 		 "DLCX: deleting connection ...\n");
 
+	if (!mgcp_endp_avail(endp)) {
+		rate_ctr_inc(&rate_ctrs->ctr[MGCP_DLCX_FAIL_AVAIL]);
+		return create_err_response(NULL, 501, "DLCX", p->trans);
+	}
+
 	/* Prohibit wildcarded requests */
 	if (endp->wildcarded_req) {
 		LOGPENDP(endp, DLMGCP, LOGL_ERROR,