We define “network sharing” as a business model in which two or more communications service providers (CSPs) share network resources through joint ownership or by third-party-enabled network sharing (open networks).It is a generic concept but is most widely applied in mobile and fiber to the home (FTTH) networks. It is technology-neutral, and includes active and passive sharing of existing as well as new infrastructure. Regulatory enforced sharing of legacy assets, such as raw copper infrastructure, is not included.