Network Function Virtualization (NFV) provides mobile telecom operators with the capability to legacy mobile core functions in virtualize network entities VNFs. This allows to offer fine-grade on-demand network services due to dynamically change of the amount of resources which handle the user traffic. - scale in/out process. Virtualization helps to decrease the OPEX of operators, but it is important to find a tradeoff between legacy and virtualised entities to be able to provide services and meet the QoS. We consider the hybrid 5G EPC core which contains both legacy and virtualized entities. The virtualized resource allocation process follows the hysteretic algorithm. The EPC Core is modelled as a queuing model with dynamically changed number of servers. © 2018 IEEE.