BT Chooses Perle Terminal Servers for Remote Access and Management


BT is one of the leading communications companies in the UK, providing broadband, phone, TV and mobile services to its customers. They wanted to update their residential phone line operations to provide a more efficient service to their customers.

One of the responsibilities of the residential phone line section of BT is to be able to remotely test phone lines when a customer reports an issue, so that it can be determined whether the line is clear and operating, or whether further investigation is required and an Engineer should be dispatched. Previously operating a mixed X.25 and Ethernet environment, the company wanted to move to a direct IP connection to their Loop Diagnostic Units (LDU). This would enable them to communicate with the exchanges at a much higher speed, allowing them to service their customers more efficiently and quickly.

Prior to the upgrade, when a residential customer reported that their phone line appeared to not be working, BT’s headquarters would complete an initial check across the X.25 network by connecting to an LDU at the exchange. This required a user on a remote network to open an application, enter the IP address and port number, and then send a command to the relevant LDU across the LAN. This command would be sent through the X.25 pads to a serial connection on the LDU, which would communicate via a serial link to request the specific line to test and then feed back to the user on the LAN. The goal for BT was to replace this X.25 WAN with a direct IP connection, but retain the LDU as this was not at the end of its lifecycle yet – it simply needed to be able to accessed over Ethernet, securely and remotely.


The Challenge

Provide BT with remote access and management of Loop Diagnostic Units (LDU’s) over Ethernet. The solution needed to meet 3 key requirements:

+ Redundancy – a backup feature to support the LDU’s in the event of loss of power

Security – meeting BT’s “Safe to Connect” standard

+ Support – local UK-based support


The Solution

+ IOLAN STS 8 DC Terminal Servers were installed at the Exchange sites, and connected to the LDU’s

Perle IOLAN STS8 DC Terminal Servers were connected to 2 fused 50v feeds

+ Extensive testing on Perle IOLAN STS Terminal Servers in order to pass BT’s “Safe to Connect” requirements

+ Technical support from Perle


The Results

+ Remote and secure access to LDU’s over IP via the Perle Terminal Servers

+ By replacing the X.25 WAN, BT is now able to communicate with the exchanges at a much higher speed

+ The dual feed from DC IOLAN Terminal Servers enabled backup redundancy to support LDU’s in the event of loss of power

The whole of the Perle IOLAN STS Terminal Server range passed the BT “Safe to Connect” requirements




Case study courtesy of Perle.