It's about a 2+ year build-out period for that $18B.
They committed a large sum last year and the year before that as well.
The $12B net profit is after infrastructure improvement. Since they have a roughly 20% gross margin in the corporation, that means 80% of gross covers expansion, labor, taxes, overhead, R&D, etc., etc.
The figure I find notable is this particular unit, wireless, is committing $18B this year to expansion and is receiving gross revenue of about that same figure, or less. For that to make sense with a 20% margin they clearly expect future revenue to provide a profit margin.
VoIP, tethering and Sling Player ought to kill that!
EDGE had/has a useful life of over 10 years. 3G is likely to almost get there. LTE (4G) is designed to morph over time so it is more akin to OSX with occasional software upgrades so the useful life gets closer to 15 years.
I have had houses far older than that. They didn't cost billions of dollars either. It takes chutzpah to invest in this industry.
Rocketman