Yes, it’s true.
I mean 3rd for the site…
For sites with 10 up to 24 TRXs we use 2 (MBI5/MBO2) or 3 (MBI3/MBO1) cabinets.
Usually they are connected via 2 A-bis links , in rare cases via 3 A-bis.
I’m sorry for the not very clear expression.
BR,
TNS