Openreach (a BT Group company tasked with installing and maintaining a significant majority of the physical telephone network in the UK) maintains a Hot-Site Register, updated every 12 months by voluntarily supplied information from the ESI companies in the UK. Any Openreach engineer visiting a site on the register must be Hot-Site trained. Certain working practices and planning considerations must be followed, such as not using armoured telephone cables, fully sealing cable joints to prevent access, over-sleeving of individual pairs of wires beyond the end of the cable sheath, and isolating (outside the Hot-Zone) any line to be worked on. It is assumed to be the responsibility of the party ordering the initial installation of a service to cover the cost of providing isolation links, service isolating devices, and clearly marked trunking for running cables, and all should be part of the planning process.