BusinessPhone Communication Platform 4.0
Facilities

## Direct Indialling (DID)

## Definition

DID denotes a function whereby a public network subscriber, by number dialling, can connect her-/himself to the wanted extension in ASB150 02. Connection from the public exchange to ASB 150 02 can be analogue or digital.

## Use

### DID to extension

DID enables all public network subscribers, without assistance from the OPERATOR, to access the relevant extension.

This means for the company a saving in the number of OPERATORs while at the same time it is easier for the callers to learn whether the called extension is free or busy.

### Calls via OPERATOR

Subscribers who do not know the DID-number dial the normal number (OPERATOR number) of the PBX and are answered in the customary manner by the OPERATOR who then extends the call.

### Diversion on busy and no reply

If a called extension does not answer, is busy or, for other reasons through-connection is not possible, it can be determined by programming whether the caller shall receive a tone message or whether the call shall be diverted to the OPERATOR.

### Types of DID

DID is no uniform function, but is dependent on the signalling principle employed by the public exchange. Contact the supplier in this respect.

## Operation

### Calls from the public network

In most DID cases the public network subscriber dials the entire number including extension number in one sequence.

For DTMF-direct indialling the subscriber also dials the entire number, but in this case ASB 150 02 gives the subscriber (caller) a new dial tone as an invitation to dial an (optional) internal number.

In the event that the subscriber does not dial any digits within a predetermined period, the call will be diverted to the OPERATOR.

### Calls to extensions

An incoming DID-call is signalled with the external ring signal at the extension telephone and, on answer, direct speech connection is established.

The called extension can initiate inquiry and transfer of the call as for all other external calls.

### Called extension does not answer

After a predetermined time the call will be diverted to the OPERATOR or other selected answering position.

### The extension is busy

The caller can receive busy tone directly or, if so programmed, can be diverted to the OPERATOR or another selected answering position.

### Dialled number does not exist, is blocked or an incomplete number has been received

The caller can receive busy or vacant tone directly. If so programmed the caller can be diverted to the OPERATOR or another selected answering position.

### Individual blocking of DID calls

You can block extensions individually to receive DID calls.

### Calls to or diversion to the OPERATOR

If a name string has been programmed for the relevant trunk, the OPERATOR receives a message on the display stating that the call is on a DID-trunk.

If the call is diverted to the OPERATOR the right‑hand side of the display will state who has been called and the reason for the diversion.

## Capacity

The number of DID - trunks solely is limited by the number of trunk board positions .

The maximum number of trunks should not exceed 60.

## Limitations

DID often means that the public network needs to be adapted for this function.

Different countries use different types of DID.

For connection purposes it must be clearly established whether the local DID-signalling is supported in ASB 150 02.

Many signal criteria are programmable in ASB 150 02, whereas others can demand other types of printed board assemblies (PBAs).

The external call number to the OPERATOR will usually need conversion to the call number used in ASB 150 02.

Some public exchanges send more or fewer digits than those in the number series used in ASB 150 02. Via command digits can be added to the external number or received first digits can be ignored.

Note that in order to be able to make incoming external calls to PBX-groups, fictive numbers etc., these must have the same number length as extension numbers.

## Programming

To obtain an overview of the relevant commands for signalling, diversion (rerouting ) prerequisites and operator directory numbers see Trunk (486/155 34-ASB 150 02 Uen).

For the programming of answer (divertee) positions for diversion and rerouting see Answer position(s) for trunks (112/155 34-ASB 150 02 Uen).

The DID-lines are to be named to allow the operator to identify diverted (rerouted) calls.

See Telephone directory (481/155 34-ASB 150 02 Uen).

### Individual blocking of DID calls

0164 |  | DID to extension enabled ?

## Equipment

For DID the hardware for the trunks must be adapted to suit the relevant type of DID.

Revision: B © Ericsson Enterprise 2003