Cannot use self service short codes

drhere

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Aug 25, 2010
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I am getting a "connection error or invalid MMI code" error when I use any self service short code. I rebooted multiple times, had my phone reconnect to the network booted in safe mode.
It was working normally for awhile, then last week it stopped. I called Tmo support and it has been escalated to a higher tier, but they can't figure it out.
I have a Nokia 6 US variant it is dual SIM. I saw some website state dual SIM phones have this issue, not sure how true that is. I am by only using one SIM.
Any ideas? Thank you.