One cell can be configured with 1 to 12 TRX (usually).
The more TRX you put in one cell, the higher the capacity (it’s non-linear)
With only one TRX, you can have max 7 channels for voice.
Go there :
Select BHT as “unknown”
Blocking = 0.02(= 2%)
Lines = 7 (7 channels)
click on Calc.
capacity of 1 TRX = 2.9erlangs (full rate)
In halfrate, you can have 14 channels –> 8.2 erlangs.
The capacity in erlangs depends on the acceptable blocking rate. By default 2%. Most operators today are choosing lower blocking (1% or 0.05%).