IP Multimedia
Subsystem Core


What it does ?

The Cirpack IMS core network aims at implementing SIP-based rich communication services for telecom operators. It operates SIP-based voice, video and messaging services for subscribers over fixed or wireless broadband access. Subscribers can access services from a variety of devices such as mobile, tablet, PC, smartphone, and regular web browser.

All these functions are integrated on the same software platform to be provisioned and operated as a single product.

Use cases

Migration to full SIP network

As the migration of the networks from TDM to VoIP is accelerating, deploying the IMS Core network paves the way to have full VoIP networks where the SIP protocol is used on the access, the core network, as well as on the interconnect side.

Triple or quadruple play deployment

Our IMS core network offers to network operators a solution for interactive multimedia services, from regular voice calls to multimedia and enriched communications. It is completed with our Multimedia Telephony Application Server for complete service offer, and comes also with an OTT application server providing access to the service through a Web browser access and mobile client application.


How it works

The IMS core network is an Interrogating Call Session Control Function (I-CSCF), Serving Call Session Control Function (S-CSCF), and a Home Subscriber Server (HSS) for fixed devices, also named User Profile Server Function (UPSF).

  • The HSS/UPSF is the IMS core database. It contains subscriber’s data such as public and private identities, authentication vector to authenticate the subscriber, registration state and filter criteria to invoke the application servers.
  • The I-CSCF is the IMS core network entry point. It selects the S-CSCF to register the subscriber depending on the HSS subscriber’s data, on the same way it routes an incoming call to the S-CSCF serving the subscriber.
  • The S-CSCF is the IMS core network registrar. Depending on the HSS subscriber’s data, it authenticates the subscriber and invokes the application servers for incoming and outgoing calls.

Some technical features

  • Scalability: virtualized and modular additional modules can be added easily to provide a scalable network from 10000 subscribers to many many millions.
  • Redundancy: active –standby; default call handling in case of AS failure
  • Openness: all interfaces are IMS compliant to work with other vendors’equipment compliant with 3GPP TS 24 229
  • Security: authentication with http digest or IMS AKA
  • User identities: public and private identities; implicit registration
  • Billing: CDR generated; Rf, Ro diameter interface
  • Standards: 3GPP TS 24.229.
Some technical features