FS-5021 --resolve stupid typo

src/switch_core_io.c

@@ -153,7 +153,7 @@ SWITCH_DECLARE(switch_status_t) switch_core_session_read_frame(switch_core_sessi
 		if (session->dmachine[i] && !switch_channel_test_flag(session->channel, CF_BROADCAST)) {
 			switch_channel_dtmf_lock(session->channel);
 			switch_ivr_dmachine_ping(session->dmachine[i], NULL);
-			switch_channel_dtmf_lock(session->channel);
+			switch_channel_dtmf_unlock(session->channel);
 		}
 	}