SIPconnect

The Oracle® Enterprise Session Border Controller supports the SIPconnect model, wherein PBXs register themselves so that service providers do not need to know IP addresses or locations in advance for static configurations. This is particularly helpful when the PBX is behind a NAT.

In the PBX registration process, the PBX creates a binding between one of its phone numbers as the address of record (AoR) and Contact-URI in the REGISTER message. The registrar knows that the single AoR actually represents many addresses, and so it registers them implicitly. However, the registrar does not return the implicit AoR number in P-Associated-URIs.

The SIPconnect feature resolves the following issues that arise from using this model:

SIP INVITEs sent to the PBX from the Registrar through the Oracle® Enterprise Session Border Controller have the Request-URI of registered contact. Because it typically ignores the To-URI, the PBX needs the Request-URI username portion to be the specific extension number being called.
With the SIP connect feature enabled, the Oracle® Enterprise Session Border Controller overwrites the Request-URI username with the To-URI username.
SIP INVITEs from the PBX have the From AoR and Contact-URI usernames of specific phones rather than of the registered AoR and Contact-URI. For the Oracle® Enterprise Session Border Controller, this means that it cannot use the allow-anonymous parameter value of register; there would be no registered user matches, and the Oracle® Enterprise Session Border Controller would reject them (with a 403 Forbidden).
With the SIP connect feature enabled, the Oracle® Enterprise Session Border Controller performs allow-anonymous checking based on the registered Via address, which is the same for all requests for the same PBX.

Modifications to Registration Caching Behavior

With the SIP connect feature enabled, Oracle® Enterprise Session Border Controller registration caching works the same way that it does with the feature disabled, with the following exceptions:

The Oracle® Enterprise Session Border Controller determines whether the destination realm has the sip-connect-pbx-reg option configured, and then:

If it is configured, the Oracle® Enterprise Session Border Controller replaces the user part of the Request-URI with the user part of the To header. When the INVITE contains a P-Called-Party-ID header, the Oracle® Enterprise Session Border Controlleruses the user part of the P-Called-Party-ID header (instead of the To header).
If it is not configured, the Oracle® Enterprise Session Border Controller determines if the destination address is for a session agent and whether that session agent has sip-connect-pbx-reg option configured. When it is configured, the Oracle® Enterprise Session Border Controller performs the same replacements described in the bullet directly above. When it is not configured, the Oracle® Enterprise Session Border Controller does not make any replacements.

When it receives an INVITE request, the Oracle® Enterprise Session Border Controller checks the incoming realm for the sip-connect-pbx-reg option.

If it is configured, the Oracle® Enterprise Session Border ControllerC uses the INVITE’s source address (instead of the AoR and Contact-URI) to search the registration cache for a matched registration entry.
If it is not configured, the Oracle® Enterprise Session Border Controller determines if the INVITE’s source address is for a session agent and whether that session agent has sip-connect-pbx-reg option configured.
When it is configured, the Oracle® Enterprise Session Border Controller replaces the user part of the Request-URI with the user part of the To header. When the INVITE contains a P-Called-Party-ID header, the Oracle® Enterprise Session Border Controlleruses the user part of the P-Called-Party-ID header (instead of the To header).

When it is not configured, the Oracle® Enterprise Session Border Controller does not make any replacements.

Configuring SIP Connect Support

You configure this feature by adding the sip-connect-pbx-reg option to the realm configuration. In addition, though this feature requires that your configuration also be set up as outlined in this section. The first two items are required, and Acme Packet recommends that you also implement the suggested additional configuration.

Required Configuration

Registration caching is enabled.
For the realm from which registrations come, the options list must include sip-connect-pbx-reg; this is new configuration introduced to support this feature. The presence of this option instructs the Oracle® Enterprise Session Border Controller to skip matching the Contact header in the INVITE request with the registered Contact of the registration entry. The Oracle® Enterprise Session Border Controller finds a registration using only the INVITE’s source address.
Alternatively, you can configure the sip-connect-pbx-reg option in the options list for a session agent. When the realm where an INVITE comes from does not have this option set, the Oracle® Enterprise Session Border Controller determines whether or not the INVITE came from a session agent. You might choose to configure session agents with this option if you do not want it applied to an entire realm. If the PBX is behind a NAT device, the session agent’s IP address for the PBX (if statically configured) must be the IP address of the NAT device. And if DNS is use, the session agent’s hostname must resolve to the NAT device’s IP address.

Suggested Additional Configuration

In the SIP ports configuration (accessed through the SIP interface configuration), the allow-anonymous parameter must be set to registered. This setting allows the Oracle® Enterprise Session Border Controller to accept SIP requests from session agents and registered endpoints only, but to accept REGISTER requests from any endpoint.
For the SIP interface that accepts registrations, the options parameter must be set to reg-via-key. This setting allows the Oracle® Enterprise Session Border Controller to use the source address of an INVITE as the key to find a registration entry in the registration cache. When the INVITE’s Contact header matches the registered Contact in the registration entry, the Oracle® Enterprise Session Border Controller accepts the INVITE request.

SIP Connect Configuration

To set the SIP connect option for a realm configuration:

In Superuser mode, type configure terminal and press Enter.
```
ORACLE# configure terminal
```
Type media-manager and press Enter to access the signaling-related configurations.
```
ORACLE(configure)# media-manager
```
Type realm-config and press Enter.
```
ORACLE(media-manager)# realm-config
```
If you are adding support for this feature to a pre-existing realm, then you must select (using the ACLI select command) the realm that you want to edit.
options—Set the options parameter by typing options, a Space, the option name sip-connect-pbx-reg with a plus sign in front of it, and then press Enter.
```
ORACLE(realm-config)# options +sip-connect-pbx-reg
```
If you type the option without the plus sign, you will overwrite any previously configured options. In order to append the new options to the realm configuration’s options list, you must prepend the new option with a plus sign as shown in the previous example.
Save and activate your configuration.

To set the SIP connect option for a SIP session agent configuration:

In Superuser mode, type configure terminal and press Enter.

Oracle® Enterprise Session Border Controller# configure terminal

Type session-router and press Enter to access the signaling-related configurations.
```
Oracle® Enterprise Session Border Controller(configure)# session-router
```
Type session-agent and press Enter.
```
ORACLE(session-router)# session-agent
```
If you are adding support for this feature to a pre-existing session agent, then you must select (using the ACLI select command) the session agent that you want to edit.
options—Set the options parameter by typing options, a Space, the option name sip-connect-pbx-reg with a plus sign in front of it, and then press Enter.
```
Oracle® Enterprise Session Border Controller(session-agent)# options +sip-connect-pbx-reg
```
If you type the option without the plus sign, you will overwrite any previously configured options. In order to append the new options to the session agent’s configuration’s options list, you must prepend the new option with a plus sign as shown in the previous example.
Save and activate your configuration.