I have recently asked an FOI about QNHs- shaded boxes, approved sources, accurate qnh, alternates and minimas etc etc.
One of his remarks was that receiving QNH from an AWS (which is approved) via phone is fine and you can use it for accurate qnh (remember within 15 mins blah blah blah).
Thinking logically (
) what's the difference between getting the AWS weather via radio or via phone? Nada. Your company might have a policy on pilots using phones in flight though.
Now, having someone on the phone listening to the automated service and then advising you over the radio, there are likely going to be differing opinions.
Some could be picky down to the finest detail and say that you are technically not being advised about the QNH from an approved source because your are actually being told by someone who may not be an approved observer (albeit their info is coming from an approved source).
Is it unsafe and going to result in tea and bikkies or a trial though? Probably not.