A mobile communications infrastructure with coordinated data session offloading of mobile subscriber devices from a primary communication medium to a secondary communication medium. The infrastructure comprises a primary communications infrastructure which provides a primary communications medium for mobile subscriber devices and a secondary communications infrastructure which provides a secondary communication medium that is accessible by authorized mobile subscriber devices. An offload management system is configured to control offload of mobile subscriber devices from the primary communication medium to the secondary communication medium during a data session with a data network based on an offload profile associated with the mobile subscriber device and resource status information relating to the available capacity of the secondary communication medium.