Diversion Module

Table of Contents

1. Admin Guide
1.1. Overview
1.2. Dependencies
1.2.1. OpenSIPS Modules
1.2.2. External Libraries or Applications
1.3. Exported Parameters
1.3.1. suffix (string)
1.4. Exported Functions
1.4.1. add_diversion(reason [[,uri], counter])
1.5. Diversion Example
2. Developer Guide
3. Contributors
3.1. By Commit Statistics
3.2. By Commit Activity
4. Documentation
4.1. Contributors

List of Tables

3.1. Top contributors by DevScore(1), authored commits(2) and lines added/removed(3)
3.2. Most recently active contributors(1) to this module

List of Examples

1.1. suffix usage
1.2. add_diversion usage

Chapter 1. Admin Guide

1.1. Overview

The module implements the Diversion extensions as per draft-levy-sip-diversion-08. The diversion extensions are useful in various scenarios involving call forwarding. Typically one needs to communicate the original recipient of the call to the PSTN gateway and this is what the diversion extensions can be used for.


The draft-levy-sip-diversion-08 is expired!! See IETF I-D tracker.

1.2. Dependencies

1.2.1. OpenSIPS Modules


1.2.2. External Libraries or Applications

The following libraries or applications must be installed before running OpenSIPS with this module loaded:

  • None.

1.3. Exported Parameters

1.3.1. suffix (string)

The suffix to be appended to the end of the header field. You can use the parameter to specify additional parameters to be added to the header field, see the example.

Default value is (empty string).

Example 1.1. suffix usage

modparam("diversion", "suffix", ";privacy=full")

1.4. Exported Functions

1.4.1. add_diversion(reason [[,uri], counter])

The function adds a new diversion header field before any other existing Diversion header field in the message (the newly added Diversion header field will become the topmost Diversion header field). The inbound (without any modifications done by the proxy server) Request-URI will be used as the Diversion URI.

Meaning of the parameters is as follows:

  • reason - The reason string to be added as the reason parameter

  • uri - The URI to be added in the header. If missing the unchanged RURI from the original message will be used.

  • counter - Diversion counter to be added to the header, as defined by the standard.

This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.

Example 1.2. add_diversion usage


1.5. Diversion Example

The following example shows a Diversion header field added to INVITE message. The original INVITE received by the user agent of sip:bob@sip.org is:

INVITE sip:bob@sip.org SIP/2.0
Via: SIP/2.0/UDP
From: "mark" <sip:mark@sip.org>;tag=ldgheoihege
To: "Bob" <sip:bob@sip.org>
Call-ID: adgasdkgjhkjha@
Contact: <sip:mark@>
Content-Length: 0

The INVITE message is diverted by the user agent of sip:bob@sip.org because the user was talking to someone else and the new destination is sip:alice@sip.org :

INVITE sip:alice@sip.org SIP/2.0
Via: SIP/2.0/UDP
Via: SIP/2.0/UDP
From: "mark" <sip:mark@sip.org>;tag=ldgheoihege
To: "Bob" <sip:bob@sip.org>
Call-ID: adgasdkgjhkjha@
Diversion: <sip:bob@sip.org>;reason=user-busy
Contact: <sip:mark@>
Content-Length: 0

Chapter 2. Developer Guide

According to the specification new Diversion header field should be inserted as the topmost Diversion header field in the message, that means before any other existing Diversion header field in the message. In addition to that, add_diversion function can be called several times and each time it should insert the new Diversion header field as the topmost one.

In order to implement this, add_diversion function creates the anchor in data_lump lists as a static variable to ensure that the next call of the function will use the same anchor and would insert new Diversion headers before the one created in the previous execution. To my knowledge this is the only way of inserting the diversion header field before any other created in previous runs of the function.

The anchor kept this way is only valid for a single message and we have to invalidate it when another message is being processed. For this reason, the function also stores the id of the message in another static variable and compares the value of that variable with the id of the SIP message being processed. If they differ then the anchor will be invalidated and the function creates a new one.

The following code snippet shows the code that invalidates the anchor, new anchor will be created when the anchor variable is set to 0.

static inline int add_diversion_helper(struct sip_msg* msg, str* s)
    static struct lump* anchor = 0;
    static int msg_id = 0;

    if (msg_id != msg->id) {
        msg_id = msg->id;
        anchor = 0;

Chapter 3. Contributors

3.1. By Commit Statistics

Table 3.1. Top contributors by DevScore(1), authored commits(2) and lines added/removed(3)

 NameDevScoreCommitsLines ++Lines --
1. Bogdan-Andrei Iancu (@bogdan-iancu)17156132
2. Daniel-Constantin Mierla (@miconda)15132820
3. Jan Janak (@janakj)10452813
4. Liviu Chircu (@liviuchircu)75837
5. Henning Westerholt (@henningw)53327
6. Saúl Ibarra Corretgé (@saghul)427411
7. Konstantin Bokarius3135
8. Razvan Crainea (@razvancrainea)3111
9. Edson Gellert Schubert31092
10. Andreas Heise2110

All remaining contributors: Vlad Paiu (@vladpaiu).

(1) DevScore = author_commits + author_lines_added / (project_lines_added / project_commits) + author_lines_deleted / (project_lines_deleted / project_commits)

(2) including any documentation-related commits, excluding merge commits. Regarding imported patches/code, we do our best to count the work on behalf of the proper owner, as per the "fix_authors" and "mod_renames" arrays in opensips/doc/build-contrib.sh. If you identify any patches/commits which do not get properly attributed to you, please submit a pull request which extends "fix_authors" and/or "mod_renames".

(3) ignoring whitespace edits, renamed files and auto-generated files

3.2. By Commit Activity

Table 3.2. Most recently active contributors(1) to this module

 NameCommit Activity
1. Bogdan-Andrei Iancu (@bogdan-iancu)Jul 2005 - Jun 2018
2. Liviu Chircu (@liviuchircu)Mar 2014 - Jun 2018
3. Razvan Crainea (@razvancrainea)Aug 2015 - Aug 2015
4. Vlad Paiu (@vladpaiu)Jun 2012 - Jun 2012
5. Saúl Ibarra Corretgé (@saghul)May 2012 - Jun 2012
6. Henning Westerholt (@henningw)Apr 2007 - May 2008
7. Daniel-Constantin Mierla (@miconda)Oct 2005 - Mar 2008
8. Konstantin BokariusMar 2008 - Mar 2008
9. Edson Gellert SchubertFeb 2008 - Feb 2008
10. Andreas HeiseOct 2007 - Oct 2007

All remaining contributors: Jan Janak (@janakj).

(1) including any documentation-related commits, excluding merge commits

Chapter 4. Documentation

4.1. Contributors

Last edited by: Bogdan-Andrei Iancu (@bogdan-iancu), Liviu Chircu (@liviuchircu), Saúl Ibarra Corretgé (@saghul), Daniel-Constantin Mierla (@miconda), Konstantin Bokarius, Edson Gellert Schubert, Jan Janak (@janakj).

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Copyright © 2004 FhG FOKUS