IMS Core

Clearwater Core is Metaswitch’s implementation of IMS built exclusively using web development methods to provide voice, video and messaging services to millions of users or IoT endpoints.

Architected from the ground up for massively scalable deployments within virtualized public, private or hybrid elastic compute clouds, Clearwater Core combines the economics of over-the-top (OTT) style service platforms with the standards compliance and reliability expected of telco-grade network solutions.

The web services-oriented design, along with the component-centric micro services philosophies adopted when architecting Clearwater Core, makes it ideal for instantiation within either hardware VM-based hypervisor infrastructures (VMware or KVM) or emerging OS container-based (Docker) environments with (Swarm or Kubernetes) Cluster management.


Clearwater Core comprises all key IMS elements, including the I-CSCF, S-CSCF and BGCF. A Charging Collection Function (CCF) converts Rf-based billing streams into file-based CDRs while the HSS Mirror eliminates unnecessary queries of the global user database.

Network operators can also deploy Clearwater Core in conjunction with other IMS components from Metaswitch, such as the Perimeta Session Border Controller (SBC) and our Access/Media Gateway Control Functions (A/MGCF). Clearwater Core works with the MetaView network management system - including the Service Assurance Server (SAS) - to present alarm monitoring, statistics and analytics.

Clearwater Core supports the management and orchestration options that are critical in software-defined service function chains built on NFV constructs. It works with a wide range of independent and open VNF managers plus management and orchestration (MANO) lifecycle operations anchored by OpenStack. This includes instantiation, configuration, startup, clustering, quiescing and termination.

IMS Core