How can I use my Samsung S4 phone functionality from my Asus Nexus 7 tablet? I got two android devices: Samsung S4 and Asus Nexus 7 where the latter does not have a SIM card. I'd like to use the phone functionality from the tablet e.g. calling and/or SMS but I don't know how. I paired the device using bluetooth and I tried with an app called MightyText but that never completed the setup. Is there a way to do what I want?
It's simple. Download the WhatsApp Messenger App on to your tablet. It's free for a whole year, then you pay $1/year to keep using it.

By default, WhatsApp isn't compatible with tablets, but there is a work-around for that...

...Right Here
You can also try Line, which is another messenging app.

Also...TextPlus has the least amount of work to setup (it's compatible with tablets), but it allows you to send texts and make calls. Though it's not as good as WhatsApp or Line

I've also tried MightyText, which works just fine. Not sure why it won't work for your phone...