I haven't heard of anyone getting to the phone interview and not progressing to the assessment day.
stevep64 makes a good point here you would have to come across as a very poor communicator over the phone to be rejected at this stage. From what I have gathered by the recruitment process and the wording of the rejection email from AirServices Australia is that the SHL testing is the be all and end all for HR to assess whether you will make a good Air Traffic Controller. In Airservices Australia words:
We have found that these tools are predictive of success in these roles.
Which is interesting considering many of the comments on here about the failure rate at the academy/field placement for those that make it through the drawn out recruitment process.