I applied online. The process took 5 months. I interviewed at BT Group (Ipswich, England) in May 2015
Interview
Assessment Centre has 4 exercises: Group discussion where you discuss with around 3 other candidates different business opportunities for BT, and which case is the best. Then there is a one-to-one interview with your line manager. In depth discussion of your CV and some other questions. Then there is a pre-prepared 10-minute presentation to be presented to the line manager about what are BT's opportunities. and the last one is a case study, where you will be given a case to analyse then discuss with one of the interviewers.