BusinessPhone Communication Platform 4.0
Facilities

## Networking – VPN Service From PSTN

## Definition/Use

There are two possibilities to build up a private network:

- Using a private network, based on leased lines from the PSTN. The leased lines are paid for regardless of the capacity that is used.
- Using the Virtual Private Network service (VPN) from the PSTN, it is possible to build up a private network without having permanent connections to the different locations.

- The VPN service has all members of the network stored in a central database and builds up the connection between the different locations on request through the public network.
- The customer has the advantages of a private network while paying only for the capacity and services used.

The VPN service in the public network (market- dependent) offers customers the service that all extensions of their network, even if located in different locations, can be reached via one common public subscriber number.

Only the extension number defines where the desired person is located, because the extension number will be translated into the real public destination number by the VPN service from the PSTN.

The VPN service from the PSTN enables the customers to create a coordinated number plan within the network by offering the possibility to mix the numbers between the different locations (see the drawing below). Called extension numbers which are not located in the home exchange will automatically seize a free trunk/route defined for VPN calls, and handed over to the VPN services from the PSTN which initiate the routing to the desired extension number.

## Operation

### Incoming calls

#### Seen from the VPN

All extensions can be reached via one common public subscriber number even if the extensions are located in different areas.

#### Seen from the ASB 150 02

Incoming calls from the VPN service from the PSTN will be treated like normal incoming external calls.

### Outgoing calls

After detecting that a vacant number has been dialled, ASB 150 02 decides to hand over the required destination number for further number analysis to the VPN service from the PSTN. The whole number for accessing the VPN service is assembled from the programmed trunk/route number, the programmed predigits and the dialled number.

If the number exists in the PSTN-VPN database the call will be established to the desired destination.

If the number does not exists in the PSTN-VPN database the caller will receive the congestion tone (market dependent) from the public network.

### Numbering plan

Extensions belonging to the different areas have a common 4-digit number plan and it is possible to mix the extension numbers in all different locations (e.g.: extension 4711, 4713 are located in A, extension 4712 is located in B and 4714 is located in C).

In each location it is possible to reach all members of a VPN by dialling a 4-digit directory number.

Example for initiating a VPN service call:

Extension 5446 calls extension 6080
Dialled digits: |  | 6080 |
Programmed trunk/route number: |  | 88 |
Programmed predigits: |  | 52304 |
Total number for the VPN service call: |  | 88 52304 6080 |

Making a call via the VPN service from the PSTN, the display shows a free programmable text, for example:

Note

Command 6501 has to be programmed in the correct way, e.g.: “NETCALL”.

## Capacity

A maximum of 20 predigits can be programmed.

The extension numbers in the network must have a fixed length of four digits and may not be programmed.

## Limitations

It is not possible to use the features LAST EXTERNAL NUMBER REDIAL and SAVED EXTERNAL NUMBER REDIAL for PSTN‑VPN numbers.

## Programming

2090 |  | VPN service from PSTN

2091 |  | Predigits sent to PSTN-VPN

2092 |  | Trunk route selected as PSTN-VPN call

6501 |  | Directory name

## Equipment

None

Revision: B © Ericsson Enterprise 2003