NetworkCarriers refer to the organizations, often private, that operate telecommunication infrastructures. The networks can be operated using cable, wireless or satellite based technologies.

NetworkCarriers work within the confines of regulations set by the respective PttAuthorities, and often define the services value added resellers can offer to end consumers (companies and/or individuals).

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Different tiers of NetworkCarriers exist. The top carriers have partnering agreements in multiple countries, and provide wholesale services to other operators. 

For top of the foodchain carriers, see http://en.wikipedia.org/wiki/Tier_1_carrier.