It's not a bunch of a large number. It is a set number of phones from well known providers from a few countries.
Basically no one wanted to pay for one Business Analyst to read documentation and make phone calls to providers. For a program that has years and millions in it.
Or worse, cause it is out of scope
Or the worst, so they could sell the "buy from the provider" bullshit
Read the article. Optus is not bothering checking. Just closing stuff off.