UAC Module

Ramona-Elena Modroiu

Daniel-Constantin Mierla

Edited by

Ramona-Elena Modroiu

Table of Contents

1. Admin Guide
1. Overview
2. Dependencies
2.1. Kamailio Modules
2.2. External Libraries or Applications
3. Exported Parameters
3.1. rr_store_param (string)
3.2. from_restore_mode (string)
3.3. from_passwd (string)
3.4. credential (string)
3.5. auth_realm_avp (string)
3.6. auth_username_avp (string)
3.7. auth_password_avp (string)
3.8. reg_db_url (string)
3.9. reg_contact_addr (string)
4. Exported Functions
4.1. uac_replace_from(display,uri)
4.2. uac_replace_from(uri)
4.3. uac_restore_from()
4.4. uac_auth()
4.5. uac_req_send()
4.6. uac_reg_lookup(uuid, dst)
5. Exported pseudo-variables
6. Remote Registration

List of Examples

1.1. Set rr_store_param parameter
1.2. Set from_restore_mode parameter
1.3. Set from_passwd parameter
1.4. Set credential parameter
1.5. Set auth_realm_avp parameter
1.6. Set auth_username_avp parameter
1.7. Set auth_password_avp parameter
1.8. Set reg_db_url parameter
1.9. Set reg_contact_addr parameter
1.10. uac_replace_from usage
1.11. uac_replace_from usage
1.12. uac_restore_from usage
1.13. uac_auth usage
1.14. uac_req_send usage
1.15. uac_reg_lookup usage
1.16. lookup remote registrations usage

Chapter 1. Admin Guide

1. Overview

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

From version 1.5.0 it has function to send SIP message from configuration file. See variable $uac_req(name) and the function uac_req_send().

Version 3.1.0 adds user registration functionality. See uac_reg_lookup() function and dedicated section for remote registration configuration.

Known limitations in this version:

  • authentication does not support qop auth-int, just qop auth;

  • CSeq not increased during authentication - the response may be rejected.

2. Dependencies

2.1. Kamailio 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”.

2.2. External Libraries or Applications

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

  • None

3. Exported Parameters

3.1. rr_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”.

Example 1.1. Set rr_store_param parameter


3.2. from_restore_mode (string)

There are 3 mode of restoring the original FROM URI:

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

  • manual” - all following replies will be restored, but not also the sequential requests - this 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”.

Example 1.2. Set from_restore_mode parameter


3.3. from_passwd (string)

String password to be used to encrypt the RR storing parameter. If empty, no encryption will be used.

Default value of this parameter is empty.

Example 1.3. Set from_passwd parameter


3.4. credential (string)

Contains a multiple definition of credentials used to perform authentication.

This parameter is required if UAC authentication is used.

Example 1.4. Set credential parameter


3.5. auth_realm_avp (string)

The definition of an AVP that might contain the realm to be used to perform authentication.

If you define it, you also need to define “auth_username_avp” (Section 3.6, “auth_username_avp (string)”) and “auth_username_avp” (Section 3.7, “auth_password_avp (string)”).

Example 1.5. Set auth_realm_avp parameter


3.6. auth_username_avp (string)

The definition of an AVP that might contain the username to be used to perform authentication.

If you define it, you also need to define “auth_realm_avp” (Section 3.5, “auth_realm_avp (string)”) and “auth_username_avp” (Section 3.7, “auth_password_avp (string)”).

Example 1.6. Set auth_username_avp parameter


3.7. auth_password_avp (string)

The definition of an AVP that might contain the password to be used to perform authentication.

If you define it, you also need to define “auth_password_avp” (Section 3.7, “auth_password_avp (string)”) and “auth_username_avp” (Section 3.7, “auth_password_avp (string)”).

Example 1.7. Set auth_password_avp parameter


3.8. reg_db_url (string)

DB URL to fetch user profiles for registration.

Example 1.8. Set reg_db_url parameter

modparam("uac", "reg_db_url",

3.9. reg_contact_addr (string)

Address to be used to build contact address. Must be at least host part, can have port and parameters. Must not include 'sip:'.

Example 1.9. Set reg_contact_addr parameter

modparam("uac", "reg_contact_addr", "")

4. Exported Functions

4.1.  uac_replace_from(display,uri)

Replace in FROM header the display name and the URI part.

display and URI parameters can include pseudo-variables.

This function can be used from REQUEST_ROUTE and from BRANCH_ROUTE.

Example 1.10. uac_replace_from 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

4.2.  uac_replace_from(uri)

Replace in FROM header the URI part without altering the display name.

URI parameter can include pseudo-variables.

This function can be used from REQUEST_ROUTE and from BRANCH_ROUTE.

Example 1.11. uac_replace_from usage


4.3.  uac_restore_from()

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

This function can be used from REQUEST_ROUTE.

Example 1.12. uac_restore_from usage


4.4.  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.

This function can be used from FAILURE_ROUTE.

Example 1.13. uac_auth usage


4.5.  uac_req_send()

This function sends a SIP message from the configuration file. The message is built out of $uac_req(...) pseudo-variable.


Example 1.14. uac_req_send usage


4.6.  uac_reg_lookup(uuid, dst)

This function sets the PV dst to SIP URI that correspond to uuid in uac registations table. uuid and dst must be pseudo-variables.

This function can be used from ANY_ROUTE.

Example 1.15. uac_reg_lookup usage


if(uac_reg_lookup("$rU", "$ru"))

5. Exported pseudo-variables

  • $uac_req(key)

Exported pseudo-variables are documented at

6. Remote Registration

The module can register contact addresses to remote REGISTRAR servers. You have to add records to uacreg table. The table stores following attributes:

  • l_uuid - local unique user id, e.g.,: 12345678

  • l_username - local user name, e.g.,: test

  • l_domain - local domain, e.g.,:

  • r_username - remote username, e.g.,: test123

  • r_domain - remote domain, e.g.,:

  • realm - remote relam, e.g.,:

  • auth_username - authentication username, e.g.,: test123

  • auth_password - authentication password, e.g.,: xxxxxx

  • auth_proxy - SIP address of authentication proxy, e.g.,:

  • expires - expiration time for registration, in seconds, e.g.,: 360

The module takes care of sending REGISTER and refresh registrations before they expire.

When calls come in, you have to run uac_reg_lookup() that will detect if the call is coming from a remote SIP provider and can change the R-URI to local username@domain. Afterwards you can run location lookup.

Example 1.16. lookup remote registrations usage

    if(uac_reg_lookup("$rU", "$ru")) {
        xlog("request from a remote SIP provider [$ou => $ru]\n");