Step 3: set 021548970 on a blacklist
The Marketing Association tries to decrease the number of spam and advertisement phone calls by running the Do Not Call service. It is a free service offered in New Zealand to decrease unsolicited marketing calls. Mostly reliable companies will subscribe to the list to avoid calling someone who did not want to.
You can register at www.marketing.org.nz
Nevertheless, there still might be businesses calling you anyway, especially when they use automated dialling systems. Please report it to the Marketing Association or your telecommunication provider.
You can also configure a blacklist on your phone system, which is a partial solution to significantly reduce the spam calls. However, it won’t be able to block all spam numbers. Check out your VOIP provider, as some offer routers that use blacklist features.
In addition, some mobile phone applications are offered for the purpose of blacklisting certain numbers or warning you when an untrustworthy number is calling. The New Zealand telecom offers different apps. Have a look here.
Of course you are tilting at windmills here. Anyhow, the more people are aware of the dangers the more they will use tools to strive against them. Thereby step by step the unsolicited calls and the scammers will be narrowed.