Has your help desk developed a complete training and induction package for new starters?
It may be that new starters know the technology inside-out, but they won't necessarily know anything about the way that your company implements technology in your workplace.
Starting a new job can be a bewildering experience, and stories of people "hitting the ground running" are worrying to me.
Someone who doesn't know your house rules may unwittingly commit a serious breach of company policy by giving information that the caller may be restricted from knowing. I had this happen to me once; a caller rang and wanted access to a server that we, as administrators, could access but, unbeknownst to me, was not open to this particular set of users. I had e-mailed a particular file to him as requested and received the telling off of my life. The user in question had been trying to obtain a particular piece of information for some time and took advantage of the new person to get what he wanted. He had waited until I was on my own, so he had been watching the office, then called me. Doing my best to be helpful, I took the call. He complained that he wasn't able to access a share on the network but explained that there was just one file he needed. I thought that the best way to get him working was to get it for him, so I did.
Later I was warned about him and had to come clean. I reacted angrily to the telling off, feeling that (a) I should not have been left alone on my first day and (b) the manager had a duty to explain the setup to me before I started to take calls.
At this point, I started to draft an induction package for new starters, which explained the various requirements of the system, the procedures for handling calls, and the levels of security involved. When I started to dig into it, I realized that there was an enormous amount of information to give new starters in order to make sure that they followed all the rules and fully understood the limitations of the position.