The reason your tablet has a phone number associated with it is so you can use Verizon data. Tablets can not make phone calls.
You can make calls from a tablet using Skype or Hangouts. Or using a Google Voice number. But these are not traditional calls like you would make with your phone.
My Elipsis 8 may be different that Elipsis 7. Elipsis 8 uses the cellular network or WiFi and has Verizon's Message+ installed. To make a phone call...1) open Message+ 2) enter the phone number or contact's number you want call, then 3) click the telephone handset icon in the top right hand corner to make the call.
You cannot make calls from a tablet. Every Verizon Wireless device comes with an phone number, this is purely for data and identification purposes.