[Galaxy S I9000 Q&A, Help & Troubleshooting] webht75:
I haven't test below steps myself, but it make sense to fix this issue.

Phone companies make Cell Phones for Europe as well as United States, but for sure, to not waste money in making different Chip Boards that can handle different kind of Frequencies, they just make the Same Identical Phone and just enable or disable some Functions.

In the United States, some carriers, in my case i have a contract with AT&T, use 3G only in the 850Mhz Band, but if you bought your Phone Unlocked and like me it came from Europe, the 850Mhz Band is disabled, so you just have to Enable the 850Mhz Band Frequency in order to be able to pick up the 3G Frequency of you Carrier here in the US.

Here is how you do it:

Open the Phone Screen and Type the following code:

* # * # 1 9 7 3 2 8 6 4 0 # * # *

The phone will automatically take you to a screen called:

SERVICE MODE

AND YOU WILL SEE THESE OPTIONS:

----------------------

[1] DEBUG SCREEN

[2] VERSION INFO

[3] UMTS RF NV

[4] GSM RF NV

[5] AUDIO

[6] COMMON

----------------------

all these options are written very very small so you will have to touch the screen very accurately to get the right one... so select them in the following order:

[1] Debug Screen

+

[8] Phone Control

+

[7] Network Control

+

[2] Band Selection

Once you Tap on "Band Selection" you will have a screen stating these 4 Options:

-------------------------

= BAND SELECTION =

[1] Automatic [*]

[2] WCDMA Band []

[3] GSM Band []

[4] Combi Bands []

-------------------------

The Asterisk ' * ' indicates what option has been chosen, in this case the selection is on "AUTOMATIC" which is correct: the Phone will pick the best Network to work, we just have to make sure that the Phone is searching in all the Possible Networks because by Default some of them are Disabled.

So Tap on:

[2] WCDMA Band []

and on the screen you will see appearing the following Options:

----------------------------------

= WCDMA BAND =

[1] WCDMA ALL []

[2] WCDMA 2100(FDD I) [*]

[3] WCDMA 1900(FDD II) [*]

[4] WCDMA 900(FDD VIII) [*]

[5] WCDMA 850 (FDD V) []

-----------------------------------

In my case, since the Telephone comes from Europe, the 850 Band is not enabled and you can tell that by the fact that it doesn't have the ' * ' beside it.

JUST TAP ON

[5] WCDMA 850 (FDD V)[]

the phone in about a second will tell you that the Option has been Enabled.

~~~To Go Back DO NOT USE THE "LOOPED ARROW" Button~~~

=== PRESS THE "MENU" BUTTON

and select "BACK" ===

now on the screen you should see the Asterisk beside all the Frequencies, like this:

----------------------------------

= WCDMA BAND =

[1] WCDMA ALL []

[2] WCDMA 2100(FDD I) [*]

[3] WCDMA 1900(FDD II) [*]

[4] WCDMA 900(FDD VIII) [*]

[5] WCDMA 850 (FDD V) [*]

----------------------------------

Now, just to make sure that we did everything right, let's press again the "MENU BUTTON" and select again "BACK" so we go back to the

" =BAND SELECTION= " Screen:

-------------------------

= BAND SELECTION =

[1] Automatic [*]

[2] WCDMA Band []

[3] GSM Band []

[4] Combi Bands []

-------------------------

This time, let's choose a different Option:

Tap On:

[4] Combi Bands []

and you will see a screen giving many more Bands Options like this:

----------------------------------

= COMBINATION BANDS =

[1] GSM 850 [*]

[2] GSM 900 [*]

[3] DCS 1800 [*]

[4] PCS 1900 [*]

[5] WCDMA 2100(FDD I) [*]

[6] WCDMA 1900(FDD II) [*]

[7] WCDMA 900(FDD VIII) [*]

[8] WCDMA 850 (FDD V) [*]

----------------------------------

Make sure that there is the ' * ' beside the "WCDMA 850 (FDD V)" if you don't see it, Tap on that Option so that it will be enabled.

And then go Back (remember you have to do that with the "MENU BUTTON" and not with the "LOOPED ARROW" Button) and make sure that all the Bands have been enabled.

If all the 8 Different Bands Options have the Asterisk beside it, you have successfully enabled all the 3G Bands available and now you will be able to access the 850Mhz 3G Network Spectrum.

ONCE YOU ARE DONE PRESS THE "MENU" BUTTON AND CHOOSE: " END "

This is it, for me it worked, now i am using my Samsung Galaxy S with AT&T 3G and for now, i didn't have any problem... i don't know if in the future AT&T will "'*****'" about this, but i really hope not.