BRITISH Telecommunications is close to launching a new mobile telephone service which could render conventional office switchboards redundant. It could also, as it combines fixed line and mobile operations in one service, create new complexities in Britain's beleaguered telephone numbering system.

Combining the latest advance in cordless telephones with the most popular digital cellular service, it will enable executives to use a single hand set at their desks, away from their desks and outside the office.