You can mix 900 and 1800 in one ultrasite.
ultra is in 2 parts, one for the 900 and one for the 1800.
the capacity max is 222 for eatch frequency.
use BB2A for TRX no EDGE
use BB2E or BB2F for TRX EDGE.
You declare ONE BCF with 6 CELL ID (6 sectors A,B,C,D,E,F)