Media service providers for different service technologies have always been developing independently in order to satisfy the requirements of their platform and become different verticals, which leads to significant drawbacks and inefficiencies in terms of development. Media service providers using cloud capability have to deal with specific signalling flows for providing media service using an interface, which significantly will increase the complexity for the provider to use different cloud infra providers. Therefore, there is a strong necessary to requirement and architecture for a standard signalling convergence of different cloud infra providers in future media service. This Recommendation specifies the signalling requirement and architecture for media service entity attachment. This draft Recommendation mainly describes high level signalling requirements and specific requirements for media infra layer, media service layer, API layer and orchestration layer.