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.
The following illustration shows forward bearer establishment with fast forward tunneling Call Flow:
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.
The following illustration shows the 3G-324M over IP components from a stack perspective and highlights the BCF library:
