Reserved Words
To improve system performance and simply configuration, the Oracle® Enterprise Session Border Controller now supports pre-defined reserved words for commonly-used URI parameters for HMR.
Reserved words retrieve values directly from the SIP message, without your needing to create rules to store them. Their function is similar to the $REMOTE_VIA_HOST and other already-defined variables. If the header or value does not exist in the SIP message, either an empty string is returned or—for Boolean uses—the value FALSE is returned.
Reserved words apply to these commonly-accessed SIP headers and their prefixes are:
- To—$TO_xxx
- From—$FROM_xxx
- Contact—$CONTACT_xxx
- Request URI—$RURI_xxx
- P-Asserted-Identity—$PAI_xxx
- P-Preferred-Identity—$PPI_xxx
- P-Called-Party-ID—$PCPID_xxx
The following table contains the list of supported reserved words and a description of each.
| Reserved Word | Description |
|---|---|
| xxx_USER | The URI name of the header without any user parameters |
| xxx_PHONE | The URI user of the header as a phone number but without visual separators; may or may not contains a leading plus sign (+) |
| xxx_HOST | The URI host of the header |
| xxx_PORT | The URI port of the header; Value set to 5060 even if it is not actually in the message |
| CALL_ID | Resolves to the Call-ID of the current SIP message; added for convenience, and is a common store rule |
| TIMESTAMP_UTC | Timestamp is RFC 3339 format: 2009-10-10T22:00:09Z or YYY-MM-DDTHH:MM:SS:PPPZ. The .PPP refers to partial seconds and is optional; time is based on UTC. |
The reserved word CRLF resolves to \r\n and is commonly used in MIME manipulation. If you are creating a new body, there might be a need for many CRLFs in the new-value parameter.
All of these operators cause additional overhead to the HMR processing because each operator requires an evaluation of the left and right sides of the expression. To speed up evaluation of new-value expressions, you can now enter escapable characters (\f, \n, \r, \t, \v) with a backslash (\) and the Oracle® Enterprise Session Border Controller will covert them to escaped characters during the compilation of the expression (i.e., ACLI configuration time).
