RGB Networks Ltd BT Phone Cable Extension BT to RJ11 (2 pin Crossover Type) for modem landlines UK not a Rollover Cable (2M or 6.5 feet): Amazon.co.uk: Electronics & Photo
No BT Master Socket in 70's Bungalow | DIYnot Forums
How to install an NTE5A master socket
Phone Socket Wiring - BT Master Socket, The Orange and White and Other Mysteries - Telecom Green Ltd
BT Phone Line Plug to RJ11 Crossover Telephone Cable Extension | Lead Cord for Modem FAX SKY box Virgin Hub | British UK BT Socket 4 Wire | White – 3m: Amazon.co.uk:
Help needed bt drop wire to master socket connection | DIYnot Forums