Sometimes you are obliged to hand over your mobile phone number so that an "authorisation code" or similar may be sent to you. Now this may be a good thing when your bank seeks to check you really do wish to transfer $50,000 to a little old lady in Russia but it's not, for example, when Facebook wishes to check if the account you have opened in a false name is really you and the like.
Grab a random phone number from them and submit that to the intrusive company which seeks to harvest your data and wait for the confirmation code or whatever to arrive. Job done.
Unless you are terminally stupid never, ever, EVER use these numbers to receive information which may be used to identify you or your data.
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"I beseech you in the bowels of Christ think it possible you may be mistaken"
Oliver Cromwell, 3rd August 1650 - in a letter to the General Assembly of the Kirk of Scotland
How do you determine whether it's safe to use? Looks like a Chinese based site (Language options are English or Chinese) - not that that alone makes it unsafe, but there appears to be no info about who owns the site or the service.
The note at the bottom of the page seems a bit of a concern.
"Please note that this is a shared temp number Australia, so please do not receive any important Sms, we will not be responsible for the losses caused".