I've previously posted my ongoing issues with ok 4g reception outdoors, hopeless reception indoors. A view of the Optus network's reception map shows it's a known issue in my area, a relatively inner Sydney suburb.
I was desperately waiting for VoWIFI.
I travel, so I have a Taiwan sourced dual SIM samsung s7 edge. Lack of working VoLTE and VoWIFI has been an ongoing frustration. Linked to my not having the Optus CSC, which could be reflashed but I might lose the dual SIM function.
After repeated conversations with Samsung and Optus, I'd all but given up. I was in Singapore, the republic of Ireland and the UK a couple of weeks ago and had a Three / Hutchinson SIM in. They sent, me a text which suggested I download the Three Inztouch app, I did, and I got VoWIFI. Fantastic. It offers VoWIFI to anyone who has any compatible android phone on their network, regardless if they bought the phone through them or not. Very handy for people who come with work phones or from other countries!
Can I suggest Optus release a similar app?