Pierre Guichet, 62, chairman of the Alcatel CIT French telecommunications unit of Alcatel Alsthom SA, was heading for a second night in jail in a fraud probe on yesterday, with the company expressing full confidence in him and rejecting the offer he made from his cell to resign: he was jailed as part of a probe into alleged overbilling of customer France Telecom for a sum estimated by newspapers at up to $375m.