BusinessPhone Communication Platform 7.0
Facilities

## ISDN SS Multiple Subscriber Number (MSN)

## Definition

The supplementary service MSN provides the possibility to assign multiple ISDN numbers for a single interface.

In ASB 150 02 this function is used for the S -Interface in order to reach and identify each calling/called/connected ISDN terminal individually.

Additional ’CLIP no screening’ functionality is used to enable, and allow, other than ASB 150 02 defined MSN’s as A/B-numbers (CLI/COL) for calls from the S‑interface.

## Use

This feature allows a direct addressing and identification of the ISDN terminals on the S-interface.

## Operation

Each S-Interface and each connected ISDN-terminal supporting its own MSN requires a corresponding directory number in ASB 150 02 to enable a proper individual identification (otherwise is the common access number used for the identification).

The ISDN directory numbers for terminals will correspond to route access numbers within ASB 150 02 (see also ISDN S‑Interface).

### Incoming call to the S-interface

#### MSN is supported by the ISDN terminals on the S‑interface

Each ISDN terminal can be reached directly by dialling its assigned MSN.

When the ISDN terminal answers the call, its programmed MSN will be sent back as connected number.

#### MSN is not supported by the terminals on the S‑interface or the use of MSN numbers isn’t permitted by programming

Only a global call can be initiated to the S-interface. Each ISDN terminal compatible to the offered bearer service can answer the call.

If MSNs are not permitted on the S-interface, although route numbers route numbers as well as the terminals are programmed with MSNs, the called party number will be discarded in the call setup message and a global call will be initiated.

### Outgoing call from the S‑interface

#### MSN is supported by the ISDN terminals on the S‑interface

If the MSN is provided by the terminal, then this number is used in the ISDN call setup message as the “calling number”, i.e. as A-number id.

If ’CLIP no screening’ is activated then there’s no calling number validation for calls from the S-interface.
If ’CLIP no screening’ is deactivated then the received calling number must match to one of the programmed MSN’s in ASB 150 02. In case of not matching then the received calling number is discarded and the programmed common access number is used as A‑number id. for the call setup from the S-interface. Further on, if the common access number is not programmed the call setup is not allowed and the call is released.

#### MSN is not supported by the ISDN terminal or the use of MSNs is not permitted by programming.

If an ISDN terminal initiates a call and there is no MSN available, the common access number of the S‑Interface will be sent as the calling number. Further on, here is the ’CLIP no screening’ functionality also valid, as above described.

## Capacity/Limitation

A MSN refers to a ASB 150 02 defined route access number. This gives a maximum of 255 routes may be configured either as MSN’s and/or common access numbers.

## Programming

### ASB 150 02

5401 |  | Create a route

3201 |  | Route members

1956 |  | MSN provided to TEs?

1959 |  | Calling number validation from TE’s?

6501 |  | Directory name

### ISDN terminal

For programming the MSN see User’s Guide of the ISDN terminal.

## Equipment

BTU-B_ or MFU.

Revision: M © Ericsson Enterprise 2005