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In a simultaneous change-over, the last two TXE4s, in Selby, North Yorkshire and Leigh-on-Sea, in Essex, were taken out of service at 06.00hrs on Wednesday 11th March 1998. |
TXE4 Conversion Plan
During 1997, BT's exchange modernisation programme was finalised and a plan was devised to replace all the remaining TXE4 exchanges throughout the country. By 10th March 1998, there were only 2 TXE4 exchanges still to be converted. These were carefully scheduled so that one would be replaced by System X and the other by System Y.
On average each replacement TXE4 exchange cost about £1 million pounds to buy, and one year to produce, test and install.
The Leigh-on-Sea exchange has been at Rectory Grove since the 1930s and the TXE4 equipment was installed in 1983. The new digital exchange cost £650,000 and serves approximately 12000 subscribers (customers).
Ian Marston, one of the key engineers on the Leigh-on-Sea changeover explains his work, pictured above:
"I was inserting an AXE10 subscriber line card to service to MDF. This took place after all the TXE4A subs line card cables to MDF were cut on the rear of the TXE4A SAS rack. This was a no going back change over here, as there were no diss wedges to pull out as in past change overs on the MDF."
In the TXD (digital) conversion programme, change overs used to involve complicated wedge systems, laced up with string to disconnect the old exchange equipment and connect the new. This did allow for the old exchange to be fairly easily brought back into use if there was a problem with the new digital switch. Later in the programme, because the new switches had been proven to be so reliable, a revised change over method of simply cutting the MDF cables to disconnect the old exchange was adopted.
UK Digital Network
Throughout the £27 billion pound conversion programme of the entire BT network, about 100 of the digital exchanges were handled 'in house' by BT's Major Build as it was cheaper than the tenders offered by both GPT and Ericsson.
System X was the original digital exchange specification developed by the British Post Office (B.P.O), Standard Telephone & Cables (S.T.C), General Electric Company (G.E.C.) and Plessey. Later production exchanges were made solely by GEC and Plessey who merged to become GPT. The first production System X exchange, a junction tandem exchange TXD14, began working in Baynard House in July 1980. And the first local exchange was installed in Woodbridge, Suffolk in 1981.
System Y was the AXE10 version bought ' off the shelf ' from the Swedish company, Ericsson. However, the Leigh-on-Sea exchange was sourced from the factory in Scunthorpe! TXD20 an AXE10 exchange opened in Keybridge House, International Switching Centre, Vauxhall, London in 1984. And the first local AXE10, in Sevenoaks, Kent was brought into service just two years later.
Ceremony
A special video-conferencing link between the two sites ensured that the ceremony was as one.
In Leigh-on-Sea... The Worshipful the Mayor of Southend-on-Sea, councillor Mrs Jean Dunn unveiled a plaque to commemorate the event.
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The Worshipful the
Mayor of Southend-on-Sea Cllr Mrs Jean Dunn opened Leigh-on-Sea's AXE 10 exchange Completing BT's UK digital network March 11th 1998 ERICSSON BT |
More importantly, this not only completed the digital network of exchanges in the Southend-on-Sea Linked Numbering Scheme, but also marked the completion of the UK local exchange modernisation programme. |
Numbering Transfers
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See some of the work which goes into making an exchange transfer a seemless task, and review the numbering schemes. |
All photographs on this page are copyrighted to Jon Rigby and appear courtesy of Still Productions. Scans kindly arranged by Lawrence Elliott.
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