Yep, Trent is 4 positions I think, NX panel. The real Trent is shown here
http://www.simsig.co.uk/discus/messages/3740/9091.html?1195561136
Simsig simulates the working of IECCs quite well, control is more or less than same (on the overview) - though none of the detail/alarm screen are shown. Most of the signallers work is phone work, and paper filing as well especially on IECCs, which simsig either doesn't simulate or simulates in a simplistic way. There is a lot of organising set swaps, S&T and PWay blocks and general 'inquires'. Real life phone calls are obviously much more complex and involved, so you need to be a dab hand at working the panel/workstation and be on the phone with a pen in hand. In real life you also get Control ringing up 'every 5 minutes' (it seems like it) asking about delays - every minute has to be accounted for!
Its a very 'on' job and can be quite stressful at times, especially in a major failure. I enjoyed my time doing it, but wouldn't recommend it for the long term. Signallers tend to get burn out after a while in complex signal centres.
I would recommend people have a look at some of the signalling rules, because tbh any fool can press buttons, the really good signallers know how to apply the rules correctly to protect safety and minimise delay. For example, often forgotten playing simsig is when examining the line you MUST block the adjoining track, because if the train you are examining with has a mishap, you'll be in double trouble if anything happens.
Its also a shame Simsig doesn't simulate single line working and engineering work, the latter uses no signals and works on voice messages only, the former handsignalmen and pilotmen.
Have a look at the following for further info
http://www.rgsonline.co.uk/Rule_Book/Forms/Live_Documents.aspx
An NX panel like Trent will need TS1 - General signalling instructions, the level crossing instructions, the Track Circuit block regs. Plus any other signalling system that applies.
You will also need to know section T, G, GSM-R, M, OTP/M, P, S, SP, TW.
If the line is electrified you will also need to know the AC/DC electrified instructions.
On top of that, not on the above site, you will need to have a copy of the sectional appendix for the area, a timetable or simplifier (obviously! - you don't get the luxury of right click on an NX panel and IECCs only give simplified timetables) relevant forms, Trust operations manual, Monthly and Weekly operating notices, box notices and local instructions - which vary in quantity, but are usually an A4 folder worth.
Above all your job is to minimise delay, you should not be building up a lot of delay under bad regulating for example - if you are getting more than 10 minutes (with 60 minutes on knock on delay) per day, start looking for another job. A lot of delay or mishaps will result in disciplinary action. You should never give trains 'adverse' change of aspect (except in emergency), drivers tend to ask for relief! Do it too many times, you'll be sacked. It should be at least years between occasions. You should also operate level crossings in time to prevent delay to road traffic, else you will get a lot of phone abuse. The same goes for occupation crossings. ****ing the public off can mean they will take chances in front of trains.