*3001#12345#*

(indent two spaces to disable formatting)

That didn't work on my iphone on att. :(

It'll work, I just have no idea how to escape special characters here, see my parent.

Works on my phone. Reminds me of phreaking. What other secret codes are there like this? How did you come to learn about this one?

It's called USSD, there's a short list on Wikipedia. A lot of them are carrier dependant, and some carrier models of certain handsets will block some codes.

https://en.wikipedia.org/wiki/Unstructured_Supplementary_Ser...

Not the OP, but I remember these codes from my first phone, a Nokia 5110.

In addition to the already mentioned code of [STAR]3001#12345# there is also [STAR]#06# which will show your IMEI.

There were plenty of others (including spelling out 'WARRANTY' to get the manufacture date of the phone) but I forgot most of them.

Interestingly, on the iPhone, dialling anything of the format [STAR]# ...anything... # will cause the screen to go grey as if a separate app, then after a short delay tell you that your code was invalid.

oh this is sweet!

For anyone who is confused:

Star #3001#12345# Start

I love how it opens up a separate app. Good stuff

That first # is extraneous. It's

    *3001#12345#*

Sorry, none of us could figure out how to escape the asterisks, how'd you do it? Feel like I'm trying to triforce here.

GP used indenting (which wraps text in (the equivalent of a) <pre>-tag -- intended for code listings and such:

  I'm an asterix * and I'm ok
  [ed: ***proof-no-space*required**]

However, a single asterix * with spaces on both sides is also "escaped": I * blink * all day and sleep all night?

So: " * #999# * " should work.

*asterisk

Yeah, formatting on HN is a bit of a dark art. This explains it: https://news.ycombinator.com/formatdoc

This one works, thanks.

Doesn't seem to work on Verizon.

Worked on my version of Verizon. Wow is that ever cool.

The extra '#' made it not work, I think. Yeah, neat!