diff --git a/lib/transport.js b/lib/transport.js
index 615e5da..3bfff9e 100644
--- a/lib/transport.js
+++ b/lib/transport.js
@@ -71,7 +71,7 @@ async function sendToModem(partner, msg, modem, parentXid, part) {
         is_outgoing: true,
     });
 
-    await sleep(1200);
+    await sleep(config.sleep_before_unlock_modem_ms || 1200);
     modemLocks.unlock(modem.name);
 
     if (msgTail) {