Disabling BT1801HG firewall

[#1]

Dear all,
I recently(ish) got a BT1801HG from PlusNet.  Does anyone know how to disable the firewall on it?  I don't mean creating a DMZ for a single machine, but turning off the firewall completely.
I'm aware that the general advice is not to turn off firewalls, however both myself and my wife have computing degrees and run Linux, so we can handle it

[#2]

Something that pops into my head whenever anybody mentions that they run Linux as a reason for not needing security;

Quote

More interesting is that most of the compromised machines were not Windows machines. "The vast majority of [the phishing sites] we saw were on rootkit-ed Linux boxes, which was rather startling. We expected a predominance of Microsoft boxes and that wasn't the case."

Taken from an atricle on El Reg last year: http://www.theregister.co.uk/2007/10/03/ebay_paypal_online_banking/
I'm not suggesting that you haven't taken care of security some other way, but I thought it worth mentioning that using a *nix system is not the whole solution - no point in helping perpetuate a dangerous myth
As far as turning off the firewall, I'm not familar with the particular router you mention - somebody who is will probably be about the place somewhere....

[#3]

If you have multiple machines then I would assume you would need an IP block so that you can turn off NAT on the router.
Turning off NAT would probably achieve what you require, although if the router does have an SPI firewall that may also need to be disabled.
Unfortunately, I'm not versed with that particular router but I'm sure someone will be able to pop along shortly and advise.
B.

[#4]

Yeah.  I don't want to run it in bridging mode as I want it to route and do NAT.  However, as my Google-foo seems to suggest, there is no way to turn off the SPI/firewall.  Therefore, I'll have to ask for an IP block.

[#5]

What I want is for all machines to be NAT'ed.  I also want all machines to be able to send outbound traffic on all ports and receive inbound (recpricol [sp?]) traffic on all ports.  So I want SPI just to pass packets from in to out and out to in.  I don't want any traffic shaping/filtering or dropping.  My issues stem from problems with VoIP (SIP and IAX) and wifi laptops not being able to ping the wired server (This router considers them to be on different networks).
I used to be able to do this with my previous router (personally purchased and now dead).  However this one (supplied by PlusNet) is a bit of an enigma to me.  There's no SSH access, so I'm left fumbling about with the web UI.