5G will be the first new mobile network designed since the emergence of software based networks. Software based networks include SDN, NFV, Cloud RAN and Mobile Edge Computing. The benefits of software based networks include agility, and reduced cost. Software based networks are the most radical change since the introduction of stored program control switching in the 1970s - the first time networking function was moved from hardware to software. Virtual Network Functions mean service providers have to consider how to assemble components into an end-to-end architecture. This will give rise to the new role of Network System Integrator. The cloud infrastructure on which the software based network runs will be designed according to the new principles of hyperscale infrastructure, where service continuity is key even though component failure is inevitable. Service providers will have to cope with a changed supply chain, with new partners. The transition to software based networks will affect service providers' staff, who will need to acquire new skills. It will mean new operating models and will result in the emergence of Network DevOps.