I have good old Nokia 6230 [which is unlocked] that I use when abroad with mu Global SIM card. How do I set the phone so that my number is hidden?

When I attempt Call Divert to Answer Phone on the phone the request is refused.

On the phone settings there is an option to divert To Another Number - should I be typing in the Global SIM card number at this point?

Thank you for help.

Please can you confirm the actual charges when using your SIM card from Singapore for sending and receiving texts also call charges to the UK And Southern Irelnd.

What would be the best SIM card (if such exists) when roaming in Austria? I notice on this site that one of the listed 'Home Countries' for Europe is 'Australia'. Is this a typo? Thanks!