MMI codes not working

Trevor Olson

New member
Nov 1, 2012
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I have a Samsung Galaxy S6 Active on the Straight Talk network. (Using AT&T towers)

I'm trying to get my voicemail to be a little better, and I can think of two way to do it...neither of which is working. Any help with this would be much appreciated!

1) Get Visual Voicemail to work:
I've tried the native visual voicemail app on my phone and when I try to set it up, I am greeted with an error that says "Looks like there is a problem with your mailbox, or you're on a plan that doesn't include Visual Voicemail. Please visit to change your data plan to one with Visual Voicemail."

I've also tried "youmail" which also isn't working...and I think it's not working because of my 2nd problem...

2) MMI codes not working. I thought I could use Google voice for my visual voicemail, and so going through their forums, I found that I am supposed to send an MMI code

**004*1XXXXXXXXXX# where the x's are my 10-digit google voice number.

when I send that code, I get an error that says "Call forwading conditionally. for All Basic Services Connection problem or invalid MMI code."

When trying to setup youmail, the same thing happens. In fact EVERY MMI code I've tried has come up with some error which ends in "invalid MMI code."

I've been on the phone with Straight Talk customer service, and they say that they've activated Conditional Call forwarding on my account, but still no luck.

So, does anyone have an idea how I can either get the native visual voicemail app to work on my phone, or get conditional call forwarding working such that I can use a third party app like google voice or youmail? Thanks for any help you can offer! I'm at my wit's end!