AdminGuide:BasicConcepts:Outbound lines
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Outbound and inbound lines
"Outbound and inbound lines" are all the SIP lines through which the PBX can make and receive calls to and from external numbers, i.e. not an internal service or extension (local SIP account).
Calls to external numbers
Calls to external numbers are not forwarded directly to the outbound lines, but are presented to the outbound routing engine. This engine decides whether the calling user/entity is authorized to perform the call (based on the destination number) and which outbound lines can be used.
Calls can reach the outbound routing engine from the numbering plan or directly as a failover action of a previous destination (e.g. an incoming call to an extension can be forwarded to an external number in case of no answer). In both cases, the requested outbound call has two associated parameters: the outbound identity and the outbound routing class.
Outbound identity
The outbound identity is the extension number used to derive the CLID for outbound calls (according to the corresponding calling number manipulation table). The Outbound Identity can be explicitly set for failover actions, while it is automatically assigned for call smade from a SIP account or for transferred/forwarded calls:
- Calls made by a SIP account
- The outbound identity is set to the extension linked to the SIP Account.
- Calls forwarded by a device (telephone-driven call forwarding)
- Same as above.
- Calls forwarded using the KalliopePBX (unconditional) call forwarding service
- The outbound identity is set to the forwarding extension number.
- Transferred calls (using KalliopePBX star-codes or telephone functions)
- The outbound identity is set equal to the transferring extension number.
In all these cases, if the caller requests to present itself as anonymous (according to the different CLIR supported methods), the outbound identity retains the extension number throughout all the lifetime of the call, and the actual calling number restriction is performed when placing the call to the outbound line (or to the destination SIP accounts for local calls).
Outbound routing class
The outbound routing class defines the actual handling of the call, i.e. whether or not it is allowed, and if so the sequence of outbound lines to be used to perform the call.
Except when explicitly set by a failover action, the choice of outbound routing class is automatically derived from the outbound identity.
Configuration
Lines can be configured in the VoIP Gateways and Domains panel.
The "Gateways and VoIP Domains" screen collects the configuration of all input/output lines from the PBX.
KalliopePBX supports both physical gateways (which interconnect the internal telephone network to analog, ASDN, or GSM lines) and VoIP terminations and trunks, using the standard SIP protocol.
It is also possible to configure multiple gateways and VoIP terminations or trunks simultaneously. Through this page you can:
- add a VoIP domain or edit an existing one;
- add a physical gateway or edit an existing one;
- add a VoIP termination or edit an existing one;
- add a VoIP trunk or edit an existing one.
The difference between VoIP terminations and trunks is due to the fact that with the former every registration/authentication account corresponds to a single phone number, while with the latter it is possible to use a range of numbers with the same authentication credentials, which usually share a common root.
N.B.: to create a VoIP termination or trunk, it is necessary to first create a VoIP domain to link it to.
The following table shows the columns in the list of outbound lines.
| Column | Description | Value |
|---|---|---|
| Enabled | Shows whether the outbound line is enabled or disabled. |   |
| Name | The name assigned to the line. | - |
| Identifier | Unique identifier assigned to the line. For VoIP terminations or trunks, this is the username for authentication. | - |
| Type | If it is not a physical gateway, this specifies the type of line. | Trunk VoIP terminal |
| State | For physical gateways with inbound registration disabled, the reachable/unreachable state shows whether or not the peer responds to SIP OPTIONS messages. If registration is enabled, it shows whether or not registration was completed successfully on the part of the gateway. For VoIP domains, the reachable/unreachable state shows whether or not the peer responds to SIP OPTIONS messages. |
    |
| RTT | Round-Trip Time of a SIP packet between PBX and gateway or PBX and VoIP domain/server of the operator. | Value in ms |
| Show | Visible if lock has NOT been acquired. Clicking the icon will show the line settings in read-only mode. |  |
| Edit | Visible only if lock has been acquired. Clicking the icon will open the line modification page. |  |
| Delete | Visible only if lock has been acquired. Clicking the icon will delete the line. |  |