You start by applying online; BT has outsourced its CSA recruitment to Manpower, so they handle most of the actual process. After a quick box-checking session and putting in some basic info, Manpower/BT will get in touch for the next step, which is a series of tests. These tests involve inputting data at speed while pre-recorded customers "speak" to you, and a couple of others, along with 130-ish personality-based statements you have to agree/disagree with.
Should you be what they're looking for, you're then told you would be contacted to arrange a phone interview; this will happen in their time, and instead of arranging a timeslot they'll ask if you can do it there and then (I did mine at 9am on a Saturday, which apparently Manpower/BT think is appropriate). If you're successful there, you're invited to the BT facility you applied to work at for an "assessment centre".
The assessment centre is like a group interview without any actual bite. The icebreaker session lasts far too long, because Manpower and BT want to know your full working history and will ask you questions related to that (and, by the way, if you have a degree you might as well forget it). The manager from BT, who was in attendance, didn't really seem to care -- her response to "what's the best thing about working here?" was "job security", which came across as "I work here because it's a job I can't really get sacked from".
You're then taken to the floor to listen in to some calls, asking questions from the CSA when you can -- you're then asked to walk the rep from Manpower and the rep from BT what happened, and whether you'd have done anything differently.
Finally, there's a group task -- a "lost at sea" exercise, which seems like it's mostly there to kill time rather than gauge any of your qualities.
The people who were with me on the assessment day were all lovely; they were all hard-working, enthusiastic people who could do great things at the company, and I hope some of them do/have. But when BT/Manpower go along the application process with a heap of apathy, right from the telephone interview to the assessment centre, I'm kind of glad I didn't get an offer.