BHCA stands for Busy Hour Call Attempts . which implies that this parameter relates to number of call attempts in a busy hour and not the number of calls made in a busy hours . suppose a subscriber attempted 5 times to make a call in a hour for a telecom switch , but the call was made through only once , then the BHCA is 5 and not 1.
Most of the telecom switches are designed on the basis of BHCA .If a switch is having a BHCA of 80000 then it indicates on this switch 80000 call attempts can be made on a busy hour and switch will be able to cater all of then , switch will not be having any instability problems.Now how many calls become successful out of these attempts is another case.