asterisk users - Jan 2010 - Broker lines on a T1 : Signaling convention?

I've been running Asterisk with a standard PRI for regular telecoms.
This is also connected to our Nortel PBX for 'ordinary users'.  The
system has been working nicely (including Cisco 7970 phones that are
connecting via SIP).

But now I'm going 'on net' with broker lines (for a trading room
environment).  The telecoms people at the other end of the connection
tell me that each line is just a "standard ARD" circuit - and terms
such as 'loopstart', 'groundstart' or 'E&M'
don't have any resonance
with them.

So : Has anyone got any hints from installing trader turrets (for
instance) about what dahdi config I need for this dedicated type of
T1?

Thanks
Martin
:-)