Basically....I bought a pre-paid V3 from Telstra everything went fine
for a couple of weeks then I received a letter from Telstra stating
that I had been making nuisance calls to a particular #, not just a
couple of calls but something like 10-15 per day continuously day after
day (these supposed calls did not show up in the recent calls made list
of the phone), now just to give an insight into the # that I was
supposed to be ringing imagine a # ... ****11** my home phone # is
****44** so it was identical to my home phone except for the double #'s
shown.

I contacted Telstra insisting that I had not made those calls to that
#....they were at a loss for any other explanation other than I had
made those calls!
I mentioned it to my dad who insisted that just as a precaution we swap
phones (handsets) he then put his Telstra sim ($10 plan) in my handset
a few days later another letter from Telstra showing that nuisance
calls were now being made from his # which was in my handset.
So we now had two members of our family recorded as having made
nuisance calls to the same # (confirmed as the same # by Telstra) and
they all originated from the same handset, my dad phoned Telstra
several times trying to make some sense of it all ...one tech said yes
the handset can do that regardless of the sim but would not explain
how, another said that it could not do that ...and a third was
undecided.

My dad took the phone to a Telstra shop and asked for the phone to be
deleted of all software and reloaded as per original specs...they said
that they could not do that but they could sell us another plan, we
explained that it was not the plan which was at fault as no matter
which sim was put in that handset the unwanted calls would appear on
that bill.

In desperation we went home and trawled the net for information on how
or what could be done ourselves we soon discovered that as a Mac
household that was doubly difficult as most of the info is PC
orientated...but eventually we did manage to flash the phone with a
stock Moto MP.....in the last three weeks according to our latest bill
there have been no more calls made other than regular ones!

So can anyone offer an explanation how a handset can make such calls
regardless as to which sim card is in it, and what could have
instigated such behavior.

As for Telstra they didn't hesitate in scrubbing all costs associated
with the bogus phone calls but were completely at a loss to explain how
it could have happened.

Just as an aside.... before going the software route to hopefully fix
the problem and just for confirmation we locked the phone away in a
draw for two days so that there could be no doubt about human
intervention and during that two days the phone bill showed 21 calls
made to the same # ....from a locked drawer?