A Mobile Virtual Network Operator (MVNO) is basically a wireless service provider that rents the network infrastructure of a larger company (called a Mobile Network Operator or MNO) to provide cell phone service to its customers.

Not all MVNOs own their own mobile core network. There are actually different categories of MVNOs depending on how much network infrastructure they manage:

Mobile Virtual Network Enabler (MVNE) Reseller (Brand Reseller): This is the simplest type of MVNO. They act basically as resellers, buying cell service in bulk from MNOs and then selling it under their own brand with little to no change. They rely entirely on the MNO's network infrastructure, including the core network.

Light MVNO: These MVNOs might handle some aspects like customer service, billing, and even own some elements of the core network, but they still depend on the MNO's core network for core functionalities.

Full MVNO (Thick MVNO): This is the category with the most network independence. They have their own core network, independent of the MNO, allowing them more control and flexibility in their service offerings. However, building and maintaining a core network is expensive and requires expertise.