GSM and GPRS Call Flows

GSM Circuit Switched Call Flows

GSM Network Example

This example shows a few cells in a GSM network. We will be referring to this diagram in several sequence diagrams and call flows.

GSM Mobile Originated Call Flow

A detailed call flow of a GSM mobile originated call.

GSM Mobile Originated Call Flow - Explore More

GSM call setup is analyzed in detail. The role of each participant is documented with a separate call flow.

GSM Location Update Sequence Diagram

How does the cellular provider know where you are? Here we look at the location updating procedure initiated by mobiles to keep the cellular provider updated on their current location.

GSM Location Update - Explore More

GSM Location Update analyzed in detail. The role of each participant is documented with a separate sequence diagram.

GSM Mobile Terminated Call Flow

In this call flow we will look at how a terminating call is handled in GSM. Setting up a terminating call is a two-step process. (1) Interrogation procedure to locate the subscriber (2) Actual call setup after the subscriber has been located.

GSM RR Call Flows

GSM Radio Resource Management (RR) Call Flows.

GSM RR Collaboration Diagram

GSM Radio Resource Management (RR) Collaboration Diagram.

GSM MM Call Flows

GSM Mobility Management (MM) Call Flows.

GSM MM Collaboration Diagram

GSM Mobility Management (MM) Collaboration Diagram.

GSM Mobile Originated SMS Session

This scenario describes the session setup for a GSM originating SMS. This sequence diagram describes the SMS signaling and data transfer between the mobile subscriber and the SMS service center.

GSM Mobile Terminated SMS Session

This scenario describes the session setup for a GSM terminating SMS. This sequence diagram describes the SMS signaling and data transfer between the SMS service center and a mobile user.

GSM Handover Call Flows

GSM Handover Call Flow (Intra MSC)

This call flow covers a simple case of call handover in GSM. Here a user has an active call and is moving from the Rockville Cell to the Bethesda Cell.

GSM Inter-MSC Handover Call Flow

This call flow describes the handover between two cells handled by different MSCs.

GSM Inter-MSC Handover Call Flow (Explore More)

Inter MSC handover is analyzed in detail. The role of each participant is documented with a separate call flow.

GSM GPRS Sequence Diagrams

GPRS Combined Attach and PDP Context Activation

The combined attach and PDP context activation of a Class B GPRS terminal will be covered here.

New SGSN Interfaces Attach and Activation

Sequence diagram listing all the interactions involving the new SGSN.

User Terminal Interfaces in Attach and PDP Activation

Sequence diagram summarizing the user terminal interactions in attach and PDP context activation.