Ah. I thought it was named after WhatsApp and was trying to ride on the tails of success. I wonder if more than just me would think that? I think it would make make sense without the "S". Just "WhatCarrier".
Either way, I like the idea but I am not going to download it. I have really limited space on my phone and while this is a useful app, it's not that important to me. It would be a really cool feature if it was built into the phone's OS or launcher.