Why?
Because I have it on my phone, on my tablet, and on my Win10 Surface Pro 6. All messages are synced between the 3 devices, and the app also has voip phone calling on any of the 3 devices. I'm not sure, but you may need to have Verizon as your cell provider to use voip in the app. Verizon is my provider, so voip works for me.
Yup, this is why I also use messages+, I carry two phones and this allows me to still receive messages, calls, and call back my clients from my personal phone using my work number. Truly awesome feature!There's another cool feature if you have an iPhone without a SIM you can make and receive calls on it just like you did with your tablet as long as your connected tO WIFI. Not sure if your tablet is an iPad but it works on that too It doesn't work in reverse though if you swap the SIM to the iphone it won't let you make and receive calls on the Android device.