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Access the iPhone's Field Test mode iOS devices
Dial *3001#12345#* to bring up the iPhone's Field Test tool, which will give you information about towers and signal strength, EDGE network, and more.

[robg adds: This worked, though I'm not sure I understand any of the info presented!]
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Access the iPhone's Field Test mode | 12 comments | Create New Account
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Access the iPhone's Field Test mode
Authored by: Chas on Jul 11, '07 08:14:36AM

I dialed the number, all I get is a message "Error performing request, No Network Service" and a Dismiss button. I thought maybe I should turn off WiFi in case it was trying the wrong network, but that had no effect.



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Access the iPhone's Field Test mode
Authored by: Chas on Jul 11, '07 08:18:53AM

Oops, it looked like I missed the final asterisk. I dialed the correct number, this time I got a voice message "your number cannot be completed as dialed.."
So it's still not working for me.



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Access the iPhone's Field Test mode
Authored by: alset on Jul 11, '07 09:52:50AM

I had both errors mentioned above and both turned out to be user-related (ie, typos).

Worked and baffled me. Can anyone with more education in this field shed some light on what we're looking at?

---
standing on the shoulders of giants



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Access the iPhone's Field Test mode
Authored by: ClassicUser on Jul 11, '07 11:24:41AM

Oddly, if you dial this directly on the keypad, it seems to work and provide the data indicated. But, if you add this number to your contacts list and select it from there, it results in the "Your call cannot be completed as dialed" recording.

I think the data presented is interesting - to determine which cell tower(s) you are in range of, as well as other connectivity details - but agree that it's not exactly "useful" to us non-telco-techies.



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Access the iPhone's Field Test mode
Authored by: Chas on Jul 11, '07 04:54:51PM

Ah, that explains the problem, I entered the number into Contacts and dialed it from there. I was able to connect when dialing manually.



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Access the iPhone's Field Test mode
Authored by: jasonp on Jul 11, '07 03:36:26PM

That's the same code that's used on some Nokia phones...

-Jason



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Access the iPhone's Field Test mode
Authored by: mariofreak85 on Jul 11, '07 06:02:10PM

I always used it to put inappropriate things on my friends phones. :D



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Access the iPhone's Field Test mode
Authored by: JeffJassky on Sep 24, '07 02:12:31AM

Yeah, lots of information.. here's all I know...

Under "Cell Information" we see a list of towers that are within our range. These towers or "sites" are ordered by signal strength. the RX:-xx is the signal strength measured in decibles (DB). The lower the number (or technically since these are negative numbers - the higher) is better. For example, -60 is a better signal than -90. The tower at the top of the list will generally be the one you're actually using. As you move/drive around your signal will transfer from tower to tower.

Other than that, you're on your own :) I'm as clueless as the rest of us when it comes to the other info...



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Access the iPhone's Field Test mode
Authored by: Robo-X on Jun 12, '09 08:13:43AM

The only thing that is needed is the Mobile Country Code (MCC) and Mobile Network Code (MNC) info if you are using the iPhone with an unsupported carrier. With that info you can create your own carrier bundle that has all the info for your carrier.

//Rob



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Access the iPhone's Field Test mode
Authored by: dcurrie1961 on Sep 08, '09 09:22:10PM

Both iphone 3Gs at my house are not working with field test mode. They both give an error message of: "Error performing request. Unknown Error" Seems odd that we would both be having the same problem. The reason I want to access this is because I am suspicious of the signal strength meter. When we downloaded the most recent update 8/09, both our meters showed stronger signal strength without any increase in connection quality or dropped or failed calls in my home. I think they changed how the signal strength meter works. Can anyone help me debug field test mode or at least explain what might be going on with the signal strength meter?



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Access the iPhone's Field Test mode
Authored by: heavyboots on Feb 04, '10 08:44:19PM

On the 3GS, the signal strength "bars" area turns into an actual number when you enter Field Test mode. I believe this is the signal strength to the tower you are currently connected to. What is odd is that on T-Mobile, I can't see an Rx Quality value for the GSM Serving Tower, but this is probably either a product of the jailbreaking or the fact that TMobile's 3G network is inaccessible as it is on a different frequency from AT&T's.



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Access the iPhone's Field Test mode
Authored by: eadsd on Jul 14, '10 02:39:15PM

It looks like AT&T has disabled this USSD feature, not Apple. (Apple probably doesn't have access to this anyway, it's a network command).

I try the code from my wife's AT&T BlackBerry Bold and I get the same "Hi" response.



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