I just listened to the Casefile podcast. I also was interested in the report about the alleged call on the mobile phone. There's been no follow-up on the issue, after it was reported in the media in the early days of the investigation.
The information appears to have come from the hostel owner, when speaking to a reporter about his son being held and interrogated.
https://www.smh.com.au/national/britts-disappearance-not-reported-for-two-days-20081002-4s6l.html
So whatever facts the police have about calls from the phone, haven't been directly revealed to the media. Instead, a reporter was trying to interpret a comment from a distraught local, who was trying to interpret a comment from his son, who was trying to interpret a question from police, who were likely trying to catch him out and elicit a confession, possibly by lying to him.
So even worse than telephone tag, I don't believe anything about the phone can be considered proven through this flow of information, except that it was found in the hostel, as only her wallet and camera are listed as missing.
I agree with the Australian coroner that nothing can be done by officials, at this stage, to figure out what happened to her.
Unfortunately, there are similar cases, past and present, all over the world, including in people's hometowns. I believe that young women (and men, and older men and women) do risky things all the time, but the people around them normally help them by, for eg., making sure they get home safe. I've done that myself, several times, even had young female strangers sleep on my couch twice because they were too confused or drunk to tell me where they lived. But, every so often, someone isn't so lucky.
I also think that parents and older brothers experience enormous guilt when a young woman dies in that way, and it's almost unbearable for them to acknowledge that they weren't there to save them. So they project that guilt onto others, especially an easy target like a foreign police force.
My own thoughts are, if there's any blame to be laid, it only belongs to an individual who caused the death of the victim, or failed to report what they knew.