AdminGuide:BasicConcepts:Outbound lines/en

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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).

These lines are configured in the Gateway and VoIP Domains panel.

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 it is allowed or not, and (in the former case) 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.