The 020 7068 0500 number goes straight into a queue, as the note beside it in the database says. I have just tried it and got through to someone in about one minute 40 seconds.
I tried the 0845 number a couple of times and selected option 2, to speak to an advisor and it was answered after a couple of secondary (further) rings. As I said on Sunday evening (the post I made on 23
rd May), there was hold music on option 2 of the 0845 number then and that was the same track as on the 020 number.
I think that selecting option 2 on the 0845 number puts the caller through to one of a number of lines/numbers. Perhaps the 020 number we have is but one of those which it puts callers through to.
It is quite possible that option 2 of the 0845 number puts each subsequent caller through to the number with the shortest waiting time. Thus, you could say that it has some degree of intelligence which balances the load on each of National Rail's call centres to minimise overall waiting times.
For timetable information, I usually use the National Rail website
www.nationalrail.co.uk or the WAP site
wap.nationalrail.co.uk
from my mobile, if I'm out and about. These can give train time within 10 or 20 seconds or so, as well as live departure information.