hi sam,
you could look at the erlang table to find out how much capacity you should have.
3 TRX = 21 channels capa
erlangB(21 channels, 60% cong) = 51 erlangs of incoming ‘offered’ traffic
you should have enough capacity to welcome 51 erlangs @ 2%
Erlang B (51 erl, 2% cong) = 62 channels
that’s about 9 TRXs
now, you have to take into account call repetition.. if each user tries to connect 3 times for one call, the actual cong% is only 20%.
–> 22.8 erlangs offered
–> you need 4.5 TRX.
Basically, you need 4 TRX with HR activated, or at least 5 TRX in FR.