Зависит от версии ПО в станции. В последних версиях есть Multi-set, позволяет объединить до трёх аппаратов. Есть главный номер и к нему присоединенные. Все будут под одним номером главного аппарата и с его свойствами. Программирование:
Multi-set creation
A multi-set can be configured from the OMC tool of Alcatel-Lucent OmniPCX Office
Communication Server. This procedure requires you to:
- choose the primary phone of the multi-set by its directory number
- add one or two secondary phones into the multi-set, specified by their own directory
numbers.
Once you have configured the multi-set in this way:
- The secondary set(s) will adopt the directory number, mailboxes and characteristics
(features, barring, dynamic routing, password, diversions, etc) of the primary phone.
- The voice and text mailboxes of each secondary set will be deleted.
The properties of the primary phone are not affected.
Note:
Secondary phones can also be removed from a multi-set during this configuration. The secondary phone
is then reset and returns to its default configuration.

Multi-set busy states
When a call arrives for a multi-set, the state of the multi-set must first be determined in order to
establish whether the call can be taken and how the call will be presented (see § Multi-set
presentation of incoming calls ).

The state of each phone can be one of:
- IDLE: Not in use.
- BUSY 1: In use, but can still receive an incoming call.
- BUSY 2: In use and cannot receive an incoming call.
The multi-set also adopts one of these states according to the states of the constituent primary
and secondary phones. This dependency is summarized in the table below which shows the
multi-set state for the different combinations of primary and secondary states.
Secondary states Primary states
IDLE BUSY1 BUSY2
IDLE IDLE BUSY1 BUSY2
BUSY1 BUSY1 BUSY1 BUSY2
BUSY2 BUSY2 BUSY1 BUSY2

В 710 уже есть. Заходим в свойства главного абонента. В средней части, ближе к верху слева видим надпись Secondary sets, справа от нее есть кнопочка с тремя точками, нажимаем, добавляем второго абонента. Жмем ОК, ОК.