I've been trying to open a Telewest junction box so that I can run another telephone point from it - I know I shouldn't but I've fiddled around with enough telephone lines in my time in flagrant disregard of contractual prohibitions to be fairly unconcerned about that.
Anyway, Telewest are so sure that they don't want you to mess about with their wiring that they use tamper-proof fixings instead of ordinary screws to close the junction box. I've tried my Screwfix get-into-anything set