If you ever asked theory to call voicemail and been told “Sorry I can’t help you with that” here is the way to get around that frustration
Create a new contact
Set the number to 101 000.
Similarly if you need to get it to call a different three digit number but the three digit number first then 000 at the end. The issue is Siri does not know how to handle three digit phone numbers.
Now asked ask Siri “Call Telstra voicemail”
Voila! Siri will now call your voicemail.