IMS registration sequence diagram

Voice in LTE network (VoLTE) is carried over an IP Multimedia Subsystem (IMS). Understanding IMS basics will understanding VoLTE signaling interactions.

This sequence diagram details the message interactions involved in IMS registration. IMS registration from a visited IMS network is covered. The interactions covered are:

• Terminal attaching to the GPRS Network.
• Terminal activates a PDP context.
• An unauthenticated IMS registration is attempted.
• IPSec security association is established between the User terminal and the P-CSCF.
• Finally the terminal performs an IPSec protected registration that completes the authentication of the network and the terminal.

IMS registration sequence diagram

Understand the registration flow for different vantage points:

• IMS Registration
• IMS Registration Poster (11x17)
• IMS Registration Overview
• Registration Interactions between Visited and Home IMS Networks
• Registration Interactions between User Equipment, the Visited Network and the Home IMS Network
• UE Role Sequence Diagram
• UE Role Collaboration Diagram
• P-CSCF Role Sequence Diagram
• P-CSCF Role Collaboration Diagram
• I-CSCF Role Sequence Diagram
• I-CSCF Role Collaboration Diagram
• S-CSCF Role Sequence Diagram
• S-CSCF Role Collaboration Diagram