Meridian/BT system migration

Hi!
(Intro)
I’ve just finished setting up a test trixbox system with a few GXP2000’s. I have one VoIP trunk and one zap trunk on a standard pstn line (x100p clone). I can dial using an 8 prefix for VoIP or 9 to go out the analogue line.

(The problem)
I am now hoping to move our small but aged 'phone system onto this but I’m unsure as to which card[s] I need to proceed. The current phone system is flat white box looking unit with Meridian in green writing on the front. It also says British Telecom and Northern Telecom on the rear. I believe this is just a 5 line analogue system into some kind of digital pbx? I whipped the termination box cover off and can see 5 orange/white pairs inside. In the hinged lowered half of the pbx there are 6 RJ11 ports which are connected to ‘upper body’ of the pbx.

What I was wondering is what is the best way to interface these lines with Asterisk/Tribox (1.2.3) with a view of either cutting out the Meridian unit totally or having the option to swap back if need be.
Am I right in thinking it is the TDM400/800 card I need to be looking at with 5 or so FXO modules? Are there any other cards worth considering and why?

Thanks!
Michael

You’ll have to find what kind of lines the “box” really use by other ways (than just the colour of wires). If it’s POTS compatible, you’d be looking at TDM800P (TDM400P stops at 4 max). Or Sangoma cards. voip-info.org is your friend: voip-info.org/wiki/view/Asterisk+hardware