# Sequence diagrams

This topic shows the normal exchange of commands and events between the network, the channelizer, the TCP, NaturalAccess, and the application during various NCC service call control operations. The following function sequences are presented:

- Inbound calls

- Outbound calls

- Overlapped sending and receiving sequence diagrams

- Disconnecting and releasing

## Inbound calls

The following illustration shows the function sequence for answering an inbound call:

The following illustration shows the function sequence for rejecting an inbound call:

The following illustration shows the function sequence for accepting an inbound call and then answering it:

The following illustration shows the function sequence for accepting an inbound call and then rejecting it:

The following illustration shows the function sequence for immediately rejecting an incoming call:

## Outbound calls

The following illustration shows the function sequence for placing an outbound call. Depending upon the switch variant, some of the intermediate messages may not occur, or may occur in a different order than shown here.

## Overlapped sending and receiving sequence diagrams

The following illustration shows the function sequence for placing a call with overlapped sending of digits:

The following illustration shows events returned while handling an inbound call with overlapped receiving of digits:

## Disconnecting and releasing

The following illustration shows the command and event interchange for a network-initiated release:

The following illustration shows the command and event interchange for an application-initiated release: