iKeyMonitor WhatsApp spy app is worth trying. It logs messages sent and received in WhatsApp, contacts. It also logs other activities such as SMS, social chats, websites visited, keystrokes inputted, surroundings and more.
This one works and its free for 2 numbers, and cheap for up to 20
https://play.google.com/store/apps/details?id=com.aironlabs.whatwebplus
Hi,
This worked for me. It has free trial,but afterwards sub is needed.
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https://play.google.com/store/apps/details?id=com.wmwl.wnotify
its the sounder unit of a wireless doorbell. it waits for a radio signal and rings when the putton outside the house is pushed. its 25$ on amazon (i googled "6168RX" the code you see on the board) https://www.amazon.com/Heath-Zenith-SL-7366-02-Wireless-Plastic/dp/B0002YSK7Y