Skip to end of metadata
Go to start of metadata

Configuration Section Format

pjsip.conf is a flat text file composed of sections like most configuration files used with Asterisk. Each section defines configuration for a configuration object within res_pjsip or an associated module.

Sections are identified by names in square brackets. (see SectionName below)

Each section has one or more configuration options that can be assigned a value by using an equal sign followed by a value. (see ConfigOption and Value below)These options and values are the configuration for a particular component of functionality provided by the configuration object's respective Asterisk modules.

Every section will have a type option that defines what kind of section is being configured. You'll see that in every example config section below.

Syntax for res_sip config objects

[  SectionName ]
ConfigOption = Value
ConfigOption = Value

On this Page

Config Section Help and Defaults

Reference documentation for all configuration parameters is available on the wiki:

The same documentation is available at the Asterisk CLI as well. You can use "config show help <res_pjsip module name> <configobject> <configoption>" to get help on a particular option. That help will typically describe the default value for an option as well.


Defaults: For many config options, it's very helpful to understand their default behavior. For example, for the endpoint section "transport=" option, if no value is assigned then Asterisk will *DEFAULT* to the first configured transport in pjsip.conf which is valid for the URI we are trying to contact.

Section Names

In most cases, you can name a section whatever makes sense to you. For example you might name a transport [transport-udp-nat] to help you remember how that section is being used.

However, in some cases, (endpoint and aor types) the section name has a relationship to its function. In the case of endpoint and aor their names must match the user portion of the SIP URI in the "From" header for inbound SIP requests. The exception to that rule is if you have an identify section configured for that endpoint. In that case the inbound request would be matched by IP instead of against the user in the "From" header.

Section Types

Below is a brief description of each section type and an example showing configuration of that section only. The module providing the configuration object related to the section is listed in parentheses next to each section name.

There are dozens of config options for some of the sections, but the examples below are very minimal for the sake of simplicity.



(provided by module: res_pjsip)

Endpoint configuration provides numerous options relating to core SIP functionality and ties to other sections such as auth, aor and transport. You can't contact an endpoint without associating one or more AoR sections. An endpoint is essentially a profile for the configuration of a SIP endpoint such as a phone or remote server.


If you want to define the Caller Id this endpoint should use, then add something like the following:


(provided by module: res_pjsip)

Configure how res_pjsip will operate at the transport layer. For example, it supports configuration options for protocols such as TCP, UDP or WebSockets and encryption methods like TLS/SSL.

You can setup multiple transport sections and other sections (such as endpoints) could each use the same transport, or a unique one. However, there are a couple caveats for creating multiple transports:

  • They cannot share the same IP+port or IP+protocol combination. That is, each transport that binds to the same IP as another must use a different port or protocol.
  • PJSIP does not allow multiple TCP or TLS transports of the same IP version (IPv4 or IPv6).


Reloading Config: Configuration for transport type sections can't be reloaded during run-time without a full module unload and load. You'll effectively need to restart Asterisk completely for your transport changes to take effect.


A basic UDP transport bound to all interfaces

Or a TLS transport, with many possible options and parameters:


(provided by module: res_pjsip)

Authentication sections hold the options and credentials related to inbound or outbound authentication. You'll associate other sections such as endpoints or registrations to this one. Multiple endpoints or registrations can use a single auth config if needed.


An example with username and password authentication

And then an example with MD5 authentication


(provided by module: res_pjsip)

A primary feature of AOR objects (Address of Record) is to tell Asterisk where an endpoint can be contacted. Without an associated AOR section, an endpoint cannot be contacted. AOR objects also store associations to mailboxes for MWI requests and other data that might relate to the whole group of contacts such as expiration and qualify settings.

When Asterisk receives an inbound registration, it'll look to match against available AORs.

Registrations: The name of the AOR section must match the user portion of the SIP URI in the "To:" header of the inbound SIP registration. That will usually be the "user name" set in your hard or soft phones configuration.


First, we have a configuration where you are expecting the SIP User Agent (likely a phone) to register against the AOR. In this case, the contact objects will be created automatically. We limit the maximum contact creation to 1. We could do 10 if we wanted up to 10 SIP User Agents to be able to register against it.

Second, we have a configuration where you are not expecting the SIP User Agent to register against the AOR. In this case, you can assign contacts manually as follows. We don't have to worry about max_contacts since that option only affects the maximum allowed contacts to be created through external interaction, like registration.

Third, it's useful to note that you could define only the domain and omit the user portion of the SIP URI if you wanted. Then you could define the user portion dynamically in your dialplan when calling the Dial application. You'll likely do this when building an AOR/Endpoint combo to use for dialing out to an ITSP.  For example: "Dial(PJSIP/${EXTEN}@mytrunk)"


(provided by module: res_pjsip_outbound_registration)

The registration section contains information about an outbound registration. You'll use this when setting up a registration to another system whether it's local or a trunk from your ITSP.


This example shows you how you might configure registration and outbound authentication against another Asterisk system, where the other system is using the older chan_sip peer setup.

This example is just the registration itself. You'll of course need the associated transport and auth sections. Plus, if you want to receive calls from the far end (who now knows where to send calls, thanks to your registration!) then you'll need endpoint, AOR and possibly identify sections setup to match inbound calls to a context in your dialplan.

And an example that may work with a SIP trunking provider

What if you don't need to authenticate? You can simply omit the outbound_auth option.


(provided by module: res_pjsip)

Allows you to specify an alias for a domain. If the domain on a session is not found to match an AoR then this object is used to see if we have an alias for the AoR to which the endpoint is binding. This sections name as defined in configuration should be the domain alias and a config option (domain=) is provided to specify the domain to be aliased. 



(provided by module: res_pjsip_acl)

The ACL module used by 'res_pjsip'. This module is independent of 'endpoints' and operates on all inbound SIP communication using res_pjsip. Features such as an Access Control List, as defined in the configuration section itself, or as defined in acl.conf. ACL's can be defined specifically for source IP addresses, or IP addresses within the contact header of SIP traffic.


A configuration pulling from the acl.conf file:

A configuration defined in the object itself:

A configuration where we are restricting based on contact headers instead of IP addresses.

All of these configurations can be combined.


(provided by module: res_pjsip_endpoint_identifier_ip)

Controls how the res_pjsip_endpoint_identifier_ip module determines what endpoint an incoming packet is from. If you don't have an identify section defined, or else you have res_pjsip_endpoint_identifier_ip loading after res_pjsip_endpoint_identifier_user, then res_pjsip_endpoint_identifier_user will identify inbound traffic by pulling the user from the "From:" SIP header in the packet. Basically the module load order, and your configuration will both determine whether you identify by IP or by user.


Its use is quite straightforward. With this configuration if Asterisk sees inbound traffic from then it will match that to Endpoint 6001.


(provided by module: res_pjsip)

The contact config object effectively acts as an alias for a SIP URIs and holds information about an inbound registrations. Contact objects can be associated with an individual SIP User Agent and contain a few config options related to the connection. Contacts are created automatically upon registration to an AOR, or can be created manually by using the "contact=" config option in an AOR section. Manually configuring a CONTACT config object itself is outside the scope of this "getting started" style document.

Relationships of Configuration Objects in pjsip.conf

Now that you understand the various configuration sections related to each config object, lets look at how they interrelate.

You'll see that the new SIP implementation within Asterisk is extremely flexible due to its modular design. A diagram will help you to visualize the relationships between the various configuration objects. The following entity relationship diagram covers only the configuration relationships between the objects. For example if an endpoint object requires authorization for registration of a SIP device, then you may associate a single auth object with the endpoint object. Though many endpoints could use the same or different auth objects.

Configuration Flow: This lets you know which direction the objects are associated to other objects. e.g. The identify config section has an option "endpoint=" which allows you to associate it with an endpoint object.

Entity RelationshipsRelationship Descriptions


  • Many ENDPOINTs can be associated with many AORs
  • Zero to many ENDPOINTs can be associated with zero to one AUTHs
  • Zero to many ENDPOINTs can be associated with at least one TRANSPORT
  • Zero to one ENDPOINTs can be associated with an IDENTIFY


  • Zero to many REGISTRATIONs can be associated with zero to one AUTHs
  • Zero to many REGISTRATIONs can be associated with at least one TRANSPORT


  • Many ENDPOINTs can be associated with many AORs
  • Many AORs can be associated with many CONTACTs


  • Many CONTACTs can be associated with many AORs


  • Zero to One ENDPOINTs can be associated with an IDENTIFY object


  • These objects don't have a direct configuration relationship to the other objects.
 Unfamiliar with ERD? Click here to see a key...



  • No labels


  1. In the section for configuring TLS, the directive for the private key file should be "priv_key_file". I'm not sure if this is a change from Asterisk 12, but in Asterisk 13 you get the error: "ERROR[8121]: config_options.c:710 aco_process_var: Could not find option suitable for category 'transport-tls' named 'privkey_file' at line 18 of" (pasted for Googlebait)

    1. It's the same in both; the sample here on the wiki is just wrong. Sorry about that (sad)


  2. Perhaps a key for the Entity Relationship diagram may help.  While the Relationship Description is helpful, the image would likely be understood more clearly with a key for the connectors.

    1. Yes, that always helps. I added an expand panel with an ERD crows foot notation key underneath the diagram.

  3. Max

    What about the case of "ip-based auth"? It's pretty common with sip trunks bound to DSL lines where upstream SIP provider does not require authentication as long as registration comes from the ip address corresponding to given DSL line. An example of registration without password would be nice.

    1. I edited the REGISTRATION section to mention that you can simply omit the outbound_auth option if authentication is not necessary.

  4. Max

    I've got mixed identity case: have to use several SIP trunks from the same provider - how will [identity] section look like in this case? I can't match on ip cause calls from different trunks will come from the same ip.

    1. You wouldn't use an identify section in that case. 

      then res_pjsip_endpoint_identifier_user will identify inbound traffic by pulling the user from the "From:" SIP header in the packet.

  5. Hello

    AoR second example (without max_contacts)

    contact=sip:[email protected]:5060

    I tried this and I got the following error.

    res_pjsip_registrar.c:740 registrar_on_rx_request: AOR '41' has no configured max_contacts. Endpoint '41' unable to register

    Do I need max_contacts entry in latest asterisk code?

    1. As the documentation says 

      Second, we have a configuration where you are not expecting the SIP User Agent to register against the AOR. 

      The quoted configuration is intended for a scenario where you will not be registering. 

      If you want to register against the AOR you should set max_contacts.

      1. Hello Rusty Newton. 

        Thank you for replying. 


  6. Ben Klang, Matt Jordan I just updated the PJSIP's objects interrelations diagram based on the content of this article.

    The diagram still lacks of details.

    I'd greatly appreciate if somebody who has better understanding on subject could help finalize the diagram upto current version of PJSIP.

    Thank you.



  7. The documentation states under Section Names:

    However, in some cases, (endpoint and aor types) the section name has a relationship to its function. In the case of endpoint and aor their names must match the user portion of the SIP URI in the "To" header for inbound SIP requests. The exception to that rule is if you have an identify section configured for that endpoint. In that case the inbound request would be matched by IP instead of against the user in the "To" header.

    But it appears that res_pjsip_endpoint_identifier_user actually matches on the "From:" header, not the "To:" header.

  8. I set the "max_contacts=1" in the AOR but I always this message:

    [Apr  6 08:21:41] WARNING[1845]: res_pjsip_registrar.c:526 register_aor_core: Registration attempt from endpoint '102' to AOR '102' will exceed max contacts of 1

    And this is happen sometime when I reboot my Grandstream.

    What can I do now to solve this issue ?

    1. I add this one "remove_existing=yes" to the type aor of the endpoint :






      And all work very well...Awesome!!!