I have always used Llama a location-based action app since the Samsung Galaxy SII days. That is approximately in 2012. From the OnePlus One to the current OnePlus 3T. That is when everything fell apart.
Llama is a location-based action app. It detects the location by using cell tower information passively and then perform an action. Change sound, turn on Wifi, launch an application etc. This is great when you need a loud tone for commute and soft whisper for the office. All this is done seamlessly in the background.
As you can see the UI is clean and simple. No programming like Tasker required. This is even simpler than a new app called e-Robot. The downside is that Llama’s developer stopped support sometime in 2014.
The Samsung S2 and the OnePlus One are both single SIM phones. The 3T is a dual SIM phone. When removing the SIM tray it will cause the Llama to stop reading cell data. No cell data, the whole app stops working. The only way to fix this is to factory reset. Reinstalling the app, clearing caches doesn’t fix this. In addition, Llama has the side effect of causing the 3T kernel to crash.
After much heartbreaking install, wipe and reinstall and with the growing trend of dual sim phones, I have decided to uninstall it permanently.
Now I am using WiFi Automatic. This app has much-reduced functionality, but at least it helps me to avoid blowing my mobile data quota. The sound volume I have to do this manually.