E1 Cable Connection to a BT ASDH NTE 4U/7A

Hello all,

I am struggling to connect my gateway to a BT ASDH NTE 4U/7A. This is providing a Q.931 ISDN service.

My gateway installation manual says I need to make a 120 ohm crossover cable using Cat5 and RJ45 connector by termianating as follows:

Pin 1---Pin 4
Pin 2---Pin 5
Pin 4---Pin 1
Pin 5---Pin 2

So I made the cable up and there isn't a Layer 1 link (customer LED is amber and not off). I have tried a straight through cable, still nothing

I have another E1 link to the same rack to a different BT unit and this connects fine to my other gateway which is exactly the same as my first gateway with exactly the same config but via a straight through patch cord.

Can anyone advise if I need to use a special cable or a special pin out to interface to a BT ASDH NTE 4U/7A, or if they have an instalaltion manual/datasheet for it please?

Thanks in advance!