Welltech Dialogic SS7 Protocols ISUP - Manual (Page 23)

Dialogic ® SS7 Protocols ISUP Programmer's Manual Issue 15
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6 Interface to Application
6.1 Introduction
All primitives at the application interface (i.e. between the ISUP module and
the user) are passed by sending messages between the modules. Each
message is of type MSG as defined in the Software Environment
Programmer’s Manual.
The basic structure of each message (irrespective of the message type) is the
same. The message contains a message header, the length of the user data
and the user data. The message must be contained in a single buffer that
should be allocated by the sending module (using the getm function) and
either released (using the relm function) or passed to another module by the
receiving module. The getm and relm functions are described in Section : 4
Interface to System Services on page 19 .
The first sub-section of this chapter describes the format of the message
header associated with each type of message and the next section describes
the format of the user data contained within the message.
6.2 Application Message - Header Format
Two primitive message types are sent between the application and the ISUP
module:
Transmit Request Message from application to ISUP
Receive Indication Message from ISUP to application.
The message structure and parameters for each primitive are defined in the
following paragraphs:
6.2.1 Transmit Request
This primitive is used by the application to send a message to the ISUP
module.
Primitive Request to ISUP
Field Name Meaning
type ISP_MSG_TX_REQ (0xc700)
id call_ref
src Application module ID
dst ISUP module ID
rsp_req 0x00
hclass 0x00
status 0x00
err_info 0x00
len Number of bytes of user data
parameters User data (Len bytes in length)