No.
Families adresses were in the papers. Their phone numbers in phone books.
It wasn't just Julie's mom, it wasn't just that one time. All the families of those three missing girls and hundreds on hundreds of other missing people families were receiving prank calls on daily basis.
It was a form of entertainment. Prank calls. From people pretending to be the missing person calling for help, or insulting them, scaring, threatening and so on.
One call was reported in the news, cause this time Julie's mother felt like this could really be Julie.
What they haven't mentioned is that there were other calls, many of them. And not only to the Moseley's house. Those kind of calls were a really BIG thing until caller ID wasn't available. It was what kids were doing where they felt bored.
Usually it was just about calling a random person, asking them random, silly question like "do you have running water in the house? yes? then go and catch it" & end the call.
Heartless, souless people were targetting people from the news, so they knew something about them (from the article) and could play like they are someone they knew, or an official. It used to be very common with missing person's cases reported in press. It wasn't just the matter of a random oddball, or group of heartless weirdos. Widely publicised case meant multiple pranksters attacking repeatedly. Even if some of them were identified, I'd seriously doubt LE had a way to identify all of them, or even significant part. And they (LE) had to be aware of prank calls popularity in other cases and the fact that they had nothing to do with the cases.
DA had known associations with human traffickers?