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@Jo3 . Can you recall when making a call with Telstra, did the 4G indicator change to 3G or stay as 4G?
Do you know someone with working 4G/LTE phone you could try their sim in your phone?
Send a private message to a moderator. Try and kick them along.
@Jo3 . Why did you switch from Telstra? Cost?
Why not just bite the bullet and return to Telstra. Just verify your phone is doing LTE calls with their sim. You've had all these weeks of being unable to use the phone.
I don't have any other suggestions.
@Jo3 . So, Telstra won't accept you as account holder of Telstra sim card, and won't accept you as account holder of TPG sim card that's not working and that both sim cards have the same number.
A moderator won't look at this thread now. You can send a private message to a moderator with a link to this thread. Or make a new thread with link back here that will be looked at in a day or so.