Kevin... as one involved in network testing before retirement, even basic phones require extensive testing before approval.
Many smaller brands offer features, but non visible operation is critical. It would take many paragraphs to detail why major networks limit the number of brands they endorse. But.. there is a good reason as a simple software glitch can cause havoc for a network.
A "Like" is always appreciated. If my advice is a solution, please mark it. I'm not a Telstra employee. 50 + years exp. in radio comms., eg mobile phones since 1963, two-way radios, base stations, antennas & pagers. One of my mottos: "Believe in yourself, and you can accomplish anything".