What is P-CSCF discovery?

P-CSCF discovery. The P-CSCF is the single entry point for all SIP messages that are sent from Tobias’s UE to the IMS. Therefore, the P-CSCF address needs to be known by the UE before the first SIP message is sent. As this address is not pre-configured in our example, it needs to be discovered by the UE.

What is P-CSCF in IMS?

The P-CSCF is an edge access function and is the entry point for a UE to request services from an IMS network. The role of this CSCF is to function as a proxy by accepting incoming requests and forwarding them to the entity that can service them.

What is IMS Signalling in LTE?

To support telephone signaling between the LTE network and telephone networks, the IMS uses SIP (Session Initiation Protocol). SIP is a standard protocol for establishing voice calls over IP networks. The code is open, and uses the ‘request-response’ model to allow communication sessions.

What is CSCF?

Ericsson Call Session Control Function (CSCF) is a central component of the IP Multimedia Subsystem (IMS), managing all signaling from the end user to services and other networks. CSCF can be deployed in multiple cloud environments, such as OpenStack, VMware, and Ericsson NFVI.

What is Mgcf?

The MGCF facilitates call control, interfacing the PS domain to the CS domain when interworking between the IMS and PSTN is required. An MGCF will control one or more IMS-MGW (IMS Media Gateways) and will be used in conjunction with a BGCF (Breakout Gateway Control Function) for calls breaking out to the PSTN/PLMN.

What is S CSCF?

Serving – Call Session Control Function. The S-CSCF is the primary node in the IMS responsible for session control. Subscribers will be allocated a S-CSCF for the duration of their IMS registration in order to facilitate routing of SIP messages as part of service establishment procedures.

What is the main function of P-CSCF in IMS terminal?

P-CSCF is Proxy-Call Session Control Function—part of its function is to authenticate the user and establish an IPsec security association with the IMS terminal.

What is the DHCP-DNS procedure for P-CSCF?

After the DHCP query, the UE performs a DNS query on the FQDN received from the DHCP server. In response to the DNS query, the IP address of the P-CSCF is returned. This is known as the DHCP-DNS procedure for P-CSCF discovery.

When to use method I or II for P-CSCF discovery?

The UE can freely select method I or II for P-CSCF discovery, if: – the UE is in the home network; or – the UE is roaming and the P-CSCF is to be discovered in the visited network.

How to get the IP address of the P-CSCF?

In these scenarios, the UE can directly query the DNS server and get the IP address of the P-CSCF. Subsequent to P-CSCF discovery, the UE can send a SIP REGISTER request to register itself in the IMS core network.

Can a UA discover CSCF IP address by DHCP?

If the IMS is serviced over ordinary wireline network, it would be more likely for a UA (User Agent) to discover CSCF IP address by DHCP mechanism (or DHCP + DNS).

What is P-CSCF discovery? P-CSCF discovery. The P-CSCF is the single entry point for all SIP messages that are sent from Tobias’s UE to the IMS. Therefore, the P-CSCF address needs to be known by the UE before the first SIP message is sent. As this address is not pre-configured in our example, it needs…