There is no evidence that any call was made from WHF.
Unfortunately, a call was made from white house farm to Jeremy's cottage, and therefore two different ways you can look at this matter!
Firstly, (a) you can look at it on the basis that Jeremy was the killer, in which he needed to be able to prove that such a call had been made from the scene to his cottage, and secondly, (b) you could look at this matter on the footing that he (Jeremy) did receive such a call and that he was not the killer...
The guilters' are guilty of ignoring any information or evidence which tends to support Jeremy Bambers innocence, rather than accepting the fact that one way or another, the call from white house farm would have needed to be established as having occurred!
The guilters', want their cake, and they want to eat it all themselves!
It stands to reason that in whatever manner the news that there was something going on back at the farmhouse, that such a call as was being claimed had been made and was recieved by Jeremy, would need to be verified!