pretty much this, why bother spending all that money on a tablet then use it for calling when you could just buy a phone for a tenner to go along with it?
or if you don't want to do that then buy a phablet like a Note 3 which is a 5.7 inch screen phone.
tablets also come in 2 different variations usually 7 or 10 inch, 10 inch is rather big and bulky and only really useful when your sitting down tbh, using it when on the move and transporting it is a pain due to it's size. 7 inch however can just about fit in large pockets, etc although no chance on slim jeans or trousers, etc, im talking big jacket pockets here or hoodies, etc.
my point being there is no way you are going to want to lug about a 10 inch tablet with you all the time as you would a mobile phone, it's just simply not feasible, a 7 inch one is doable but again not really suitable imo.
a note 3 imo is probably the biggest you could get away with for day to day usage.
you could probably pick up the original note now for peanuts but again, what is the point? i would rather own a decent tablet like the original nexus 7 and cheap ZTE or Huwaei smartphone than just a Note 1 tbh.