UAC 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. restore_mode (string)
1.3.2. restore_passwd (string)
1.3.3. rr_from_store_param (string)
1.3.4. rr_to_store_param (string)
1.3.5. force_dialog (int)
1.4. Exported Functions
1.4.1. uac_replace_from([display],uri) uac_replace_to([display],uri)
1.4.2. uac_restore_from() uac_restore_to()
1.4.3. uac_auth()
1.4.4. uac_inc_cseq()
2. Frequently Asked Questions
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. Set restore_mode parameter
1.2. Set restore_passwd parameter
1.3. Set rr_from_store_param parameter
1.4. Set rr_to_store_param parameter
1.5. Set force_dialog parameter
1.6. uac_replace_from/uac_replace_to usage
1.7. uac_restore_from/uac_restore_to usage
1.8. uac_auth usage
1.9. uac_inc_cseq usage

Chapter1.Admin Guide


UAC (User Agent Client) module provides some basic UAC functionalities like FROM / TO header manipulation (anonymization) or client authentication.

If the dialog module is loaded and a dialog can be created, then the auto mode can be done more efficiently.


1.2.1.OpenSIPS Modules

The following modules must be loaded before this module:

  • TM - Transaction Module.

  • RR - Record-Route Module, but only if restore mode for FROM URI is set to auto.

  • UAC_AUTH - UAC Authentication Module.

  • Dialog Module, if force_dialog module parameter is enabled, or a dialog is created from the configuration script.

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.restore_mode (string)

There are 3 mode of restoring the original headers (FROM/TO) URI:

  • none - no information about original URI is stored; restoration is not possible.

  • manual - all following replies will be restored, except for the sequential requests - these must be manually updated based on original URI.

  • auto - all sequential requests and replies will be automatically updated based on stored original URI.

This parameter is optional, it's default value being auto.

Example1.1.Set restore_mode parameter


1.3.2.restore_passwd (string)

String password to be used to encrypt the RR storing parameter (when replacing the TO/FROM headers). If empty, no encryption will be used.

Default value of this parameter is empty.

Example1.2.Set restore_passwd parameter


1.3.3.rr_from_store_param (string)

Name of Record-Route header parameter that will be used to store (encoded) the original FROM URI.

This parameter is optional, it's default value being vsf.

Example1.3.Set rr_from_store_param parameter


1.3.4.rr_to_store_param (string)

Name of Record-Route header parameter that will be used to store (encoded) the original TO URI.

This parameter is optional, it's default value being vst.

Example1.4.Set rr_to_store_param parameter


1.3.5.force_dialog (int)

Force create dialog if it is not created from the configuration script.

Default value is no.

Example1.5.Set force_dialog parameter

modparam("uac", "force_dialog", yes)

1.4.Exported Functions

1.4.1. uac_replace_from([display],uri) uac_replace_to([display],uri)

Replace in FROM/TO header the display name or/and the URI part.

Both parameters are string. The display is optional. If missing, only the URI will be changed in the message.

IMPORTANT: calling the function more than once per branch will lead to inconsistent changes over the request.Be sure you do the change only ONCE per branch. Note that calling the function from REQUEST ROUTE affects all the branches!, so no other change will be possible in the future. For per branch changes use BRANCH and FAILURE route.

This function can be used from REQUEST_ROUTE, BRANCH_ROUTE and FAILURE_ROUTE.

Example1.6.uac_replace_from/uac_replace_to usage

# replace both display and uri
# replace only display and do not touch uri
# remove display and replace uri
# remove display and do not touch uri
# replace the URI without touching the display
uac_replace_from( , "");

1.4.2. uac_restore_from() uac_restore_to()

This function will check if the FROM/TO URI was modified and will use the information stored in header parameter to restore the original FROM/TO URI value.

NOTE - this function should be used only if you configured MANUAL restoring of the headers (see restore_mode param). For AUTO and NONE, there is no need to use this function.

This function can be used from REQUEST_ROUTE.

Example1.7.uac_restore_from/uac_restore_to usage


1.4.3. uac_auth()

This function can be called only from failure route and will build the authentication response header and insert it into the request without sending anything. Credentials for buiding the authentication response will be taken from the list of credentials provided by the uac_auth module (static or via AVPs).

As optional parameter, the function may receive a list of auth algorithms to be considered / supported during authentication:

  • MD5, MD5-sess

  • SHA-256, SHA-256-sess (may be missing, depends on lib support)

  • SHA-512-256, SHA-512-256-sess (may be missing, depends on lib support)

Note that the CSeq is automatically increased during authentication.

This function can be used from FAILURE_ROUTE.

NOTE: when used without dialog support, the uac_auth() function cannot be used for authenticating in-dialog requests, as there is no mechanism to store the CSeq changes that are required for ensuring the correctness of the dialog. The only exception are BYE messages, which are the last messages within a call, hence no further adjustments are needed. The function can still be used for authenticating the initial INVITE though.

Example1.8.uac_auth usage

failure_route[check_auth] {
    if ($T_reply_code==407) {
        if (uac_auth("MD5,MD5-sess")) {
            # auth is succesful, just relay
        # auth failed (no credentials maybe)
        # so continue handling the 407 reply

1.4.4. uac_inc_cseq()

This function can be called to increase the CSeq of an ongoing request.

It receives as the cseq parameter the value that the CSeq should be incremented with.

This function can be used from REQUEST_ROUTE, BRANCH_ROUTE and FAILURE_ROUTE.

Example1.9.uac_inc_cseq usage


Chapter2.Frequently Asked Questions



What happened with auth_username_avp, auth_realm_avp and auth_password_avp parameters

Due some restructuring of the UAC auth modules, these parameters were moved into the "uac_auth" module. This module is now responsible for handling all the credentials (static defined or dynamically defined via AVPs). The UAC module will still see the credentials defined via the AVPs.


Where can I find more about OpenSIPS?

Take a look at


Where can I post a question about this module?

First at all check if your question was already answered on one of our mailing lists:

E-mails regarding any stable OpenSIPS release should be sent to and e-mails regarding development versions should be sent to .

If you want to keep the mail private, send it to .


How can I report a bug?

Please follow the guidelines provided at:


3.1.By Commit Statistics

Table3.1.Top contributors by DevScore(1), authored commits(2) and lines added/removed(3)

NameDevScoreCommitsLines ++Lines --
1. Bogdan-Andrei Iancu (@bogdan-iancu)1287542081076
2. Ovidiu Sas (@ovidiusas)3584031351
3. Razvan Crainea (@razvancrainea)3224560148
4. Liviu Chircu (@liviuchircu)2416299290
5. Daniel-Constantin Mierla (@miconda)151113888
6. Vlad Patrascu (@rvlad-patrascu)105150175
7. Maksym Sobolyev (@sobomax)103168294
8. Vlad Paiu (@vladpaiu)8524318
9. Andreas Heise73105129
10. Edson Gellert Schubert510201

All remaining contributors: Elena-Ramona Modroiu, Henning Westerholt (@henningw), Konstantin Bokarius, Peter Lemenkov (@lemenkov), Dan Pascu (@danpascu), Dusan Klinec (@ph4r05), Jesus Rodrigues, Sergio Gutierrez.

(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/ 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

Table3.2.Most recently active contributors(1) to this module

NameCommit Activity
1. Razvan Crainea (@razvancrainea)Aug 2010 - Aug 2023
2. Ovidiu Sas (@ovidiusas)Mar 2011 - Jun 2023
3. Bogdan-Andrei Iancu (@bogdan-iancu)Jun 2005 - Apr 2023
4. Vlad Patrascu (@rvlad-patrascu)May 2017 - Mar 2023
5. Maksym Sobolyev (@sobomax)Mar 2021 - Feb 2023
6. Liviu Chircu (@liviuchircu)Mar 2014 - Feb 2023
7. Peter Lemenkov (@lemenkov)Jun 2018 - Jun 2018
8. Dusan Klinec (@ph4r05)Dec 2015 - Dec 2015
9. Vlad Paiu (@vladpaiu)Aug 2011 - Sep 2015
10. Sergio GutierrezNov 2008 - Nov 2008

All remaining contributors: Dan Pascu (@danpascu), Daniel-Constantin Mierla (@miconda), Konstantin Bokarius, Edson Gellert Schubert, Henning Westerholt (@henningw), Jesus Rodrigues, Andreas Heise, Elena-Ramona Modroiu.

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



Last edited by: Razvan Crainea (@razvancrainea), Bogdan-Andrei Iancu (@bogdan-iancu), Vlad Patrascu (@rvlad-patrascu), Peter Lemenkov (@lemenkov), Liviu Chircu (@liviuchircu), Ovidiu Sas (@ovidiusas), Daniel-Constantin Mierla (@miconda), Konstantin Bokarius, Edson Gellert Schubert, Jesus Rodrigues, Elena-Ramona Modroiu.

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Copyright 2005-2009 Voice Sistem SRL