Sprint released an economic study by an University of California at Irvine, David Neumark, said flatly that AT&T's merger history showed that is has eliminated over 100K jobs since 2002.
There are a bunch of other figures that used numbers based on assumptions. That happened on both sides in this particular matter. What is given is that mergers ultimately mean job losses due to duplication, especially in this case where both companies are in the same market. After all, mergers between two companies in the same market is to create value and eliminate waste.
Now, if AT&T had bought a supermarket chain, I would be more prone to agree that it is not not as likely to cut jobs. After all, it's unlike that its wireless customer service reps are going to be expected to be working at checkout counters or stocking shelves.
And while AT&T did promise to bring back 5K jobs, it did not promise it would not cut jobs elsewhere.
This merger between AT&T and T-Mobile is about killing off a competitor. AT&T is looking to knock off the only other GSM operator in the US. No more, no less.