# BICC Call Control and IP Bearer Control Overview

The NaturalAccess BICC implementation included with Dialogic® NaturalAccess™ Signaling Software supports:

- BICC Call Control, as an ISUP Call Control variant

- BICC APM Transport Mechanism

For more information, refer to the Dialogic® NaturalAccess™ ISUP Layer Developer's Reference Manual.

To perform IP Bearer control, BICC messages (Call Control or APM) are used to tunnel the IP bearer-related information, such as Bearer Characteristics, Codec, and IPBCP. IPBCP (IP Bearer Control Protocol) is a protocol based on SDP, and is used to exchange Bearer IP Addresses, RTP port numbers, and Packetization Time.

To format and parse Bearer Control Messages, a new library called BCF (Bearer Control Functions) is provided in the Video Access 3.3 package.

Two Bearer Control Signaling Call Flows are implemented by vmsamp_ip324m_bicc and demonstrate the usage of the BCF library:

- Forward bearer establishment with fast forward tunneling

- Forward bearer establishment with delayed forward tunneling (and optional codec negotiation)

These two call flows are commonly used call flows in a 3GPP BICC IP Core Network.

Several other call flows are possible, but are not implemented in vmsamp_ip324m_bicc, even though the BCF library would allow implementing them.

In particular, backward bearer establishment call flows are not implemented by vmsamp_ip324m_bicc. Scenarios involving COT message are also not implemented.

## Call Flow: Forward Bearer Establishment with Fast Forward Tunneling

The following illustration shows forward bearer establishment with fast forward tunneling Call Flow:

## Call Flow: Forward Bearer Establishment with Delayed Forward Tunneling

The following illustration shows forward bearer establishment with delayed forward tunneling Call Flow:

vmsamp_ip324m_bicc supports both inbound and outbound BICC call control, so the same (reverse) call flow is implemented when vmsamp_ip324m_bicc initiates the call.

## 3G-324M over IP Components

The following illustration shows the 3G-324M over IP components from a stack perspective and highlights the BCF library: