Verizon vs. AT&T or Cingular vs. Sprint vs. Nextel vs. T-Mobile

I had a face-off of US wireless providers (cell phone companies). I combined Cingular (old name) and AT&T (new name) but left Sprint and Nextel, now one company, separate because they're still separate brands and because this way we can see their individual trends before the merger. But first, let's list them according to subscribers (customers) as of mid-2008:

1. AT&T 73 million
   
2. Verizon 69 million
   
3. Sprint Nextel 52 million
   
4. T-Mobile 32 million
   

Google-popularity mirrored the customer base except for no. 2 Verizon besting no. 1 AT&T. What is more, Verizon showed a constantly increasing trend while AT&T's trend at first followed Verizon but then about mid-2007 started to decline. Pre-merger, Nextel's customer base was smaller than Sprint's but they still were more popular: advertising advantage? Also, the Nextel side of the new company has been doing worse than the Sprint side after the merger, in other words the Nextel brand has lost proportionally more customers than the Sprint one. This was reflected in their declining trend after-merger.