rolled out on existing networks, wireless carriers focus on the most populated areas first. We're excited about the prospects of better serving our customers with the additional tower solution satisfying their network demands.
The pro forma company will have a very high quality diversified mix of revenues. 88% of the pro forma company comes from wireless telephony customers with 81% of the revenue investment grade. As depicted in the pie chart on Page 8, 76% of the pro forma company's revenues come from the Big 4 wireless carriers which is the highest exposure of any tower company.
The combined companies' superior tower footprint comes at a time when wireless carriers are focusing on improving their network quality while also enhancing their networks to deliver high speed wireless data service.
In addition, with the conclusion of the AWS auctions here recently, wireless carriers have begun to announce their network build plans, bringing brand new networks to many U.S. cities as announced by Leap earlier and the deployment of the new next generation technologies as announced by T- Mobile this morning with their 3G announcement. In addition to that, wireless carriers are also announcing new technology roll outs such as Sprint's announced intentions to deploy 4G wireless broadband technology, and that's in addition to the current wireless broadband deployment already underway by ClearWire.
With the most towers in the top 50 and top 100 BTA’s, Crown Castle is best positioned to assist wireless carriers with their growth initiatives. The first places to see new networks deployed for wireless applications introduced, as mentioned before, are urban markets and with the most towers in those markets, Crown Castle is ready to help by leveraging our people, systems and processes along with the new folks from Global Signal to enable our customers to deploy very quickly.
And then finally before I turn the call over to Ben, I would like to just make that one last point. As mentioned in the beginning, though there are certainly synergies in a combination such as this, it's not the synergies that drove this transaction. This transaction is about growth and our focus on maximizing recurring cash flow per share. We believe this combination enhances our ability to achieve our long term goal of 20% to 25% growth in annual recurring cash flow per share and that is what drove our decision to merge with Global Signal.
With that, let me turn the call over to Ben Moreland who will discuss transaction details and the financial impact of this transaction.
Thank you, John, and we'll move through this pretty quickly. Some of this is actually quite simple, which is nice.
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