The application uses the Bearer Control Functions (BCF) library to format and parse Bearer Control messages. In the context of the BCF library, a Bearer Control (BCF) Message consists of the following field sequence:
APM’2000 Originating Address
APM’2000 Destination Address
Bearer Associated Transport (BAT) Application Service Element (ASE) Encapsulated Application Information, as specified in ITU-T Q765.5
The Bearer Control Message types that can be formatted and parsed using the BCF library and the main fields they encapsulate are:
| Bearer Control Message Type | Main Fields Encapsulated |
| FAST_FORWARD_BEARER_SETUP_REQUEST | IPBCP Request
Bearer Characteristics |
| FAST_FORWARD_BEARER_SETUP_ANSWER | IPBCP Answer |
| DELAYED_FORWARD_BEARER_INFO_REQUEST | Optional Codec List
Bearer Characteristics |
| DELAYED_FORWARD_BEARER_INFO_ANSWER | Optional available Codec List
Optional Selected Codec |
| DELAYED_FORWARD_BEARER_SETUP_REQUEST | IPBCP Request |
| DELAYED_FORWARD_BEARER_SETUP_ANSWER | IPBCP Answer |
The BCF library complies with the following specifications:
ITU-Q1902.4
ITU-Q1970, IETF RFC 4566 (SDP), 3GPP TS 29.414
BICC Bearer Control Tunneling Protocol (ITU-Q.1990)
BAT ASE (Q.765.5)
The BCF can build and parse Bearer Control messages according to APM’2000 User Application. To send a Bearer Control message, the application needs to:
Build the Bearer Control message using the BCF library
Use the Dialogic® NaturalAccess™ BICC Layer to attach the Bearer Control message to a BICC Call Control (usually IAM) or APM message using the Application Transport Parameter IE
To receive a Bearer Control message, the application needs to:
Use the Dialogic® NaturalAccess™ BICC Layer to get the Bearer Control message attached to a BICC Call Control or APM message
Parse the Bearer Control message using the BCF library
For more information, refer to the Dialogic® NaturalAccess™ ISUP Layer Developer's Reference Manual.