I am back in Blighty, at least for the short term, and have (deliberately) missed a few calls originating from Australia to my Optus Australian mobile phone.

I have now received a message saying that I am out of credit.

Would missing some calls from Aus really use up what must have been about $50 of credit?

Yes, I live & work in Melbourne but had to attend a meeting in New Zealand, received 3 incoming calls (redirected voicemail) and 1 outgoing call to the wife to tell her I'd arrived safely
$438

Yes, you have to be really careful about overseas calls - it does sound a bit steep but you never can tell with Optus

I had three when I visited. My bill was $400 for 3 weeks. But I did call Australia every night and text a few times too.

Sounds to me like you should switch it off and buy a cheap UK one!

It goes like this

Your Aus Number 044!!!XXX

When your away

Someone dials you You dont answer

Call to 044!!!XXX <- This gets you charged for incoming when

044!!!XXX dials your Voicemail in Aus <- You are charged for this as well as the current call to you

So you are paying for a incoming and outgoing call

You dial 121 to hear message

044!!!XXX dials your Voicemail in Aus <- You are charged for this

You listen to message from your mobile provider saying your last bill is due.

3 like home is still good for this.

Free incoming calls when roaming on 3 or Vodafone in the UK.

Not that anyone could sign up for 3 these days I guess?