Changes in Android’s operating system are due to the fact that on some phones it is not possible to receive voice alarms when Ontech alerts. An alternative could be to set a special sound instead when SMS arrives from an Ontech telephone number. You do this completely outside the app. See also this link:

How to set custom text tones for your contacts on Android

There are GSM antennas with cable that allow you to place the antenna a bit away from the device and thus look for the best antenna location. It must be a GSM antenna and it must have an SMA-type male connector.

In Android 6, you must agree that the app may send SMS or the application will stop. You can do this by:
Go to Settings / Programs / Program Manager / Ontech. Then allow SMS and right to read.