mohan bro you don't need an unlocked iphone as you are with ATT. Also they will not charge you for data plan unless you want and request. You can use internet whereever you can connect to Wi-Fi. Nirdhakka bhayera kine huncha pareko ma behoraula hehe

thanks bhakte dai ,  but read this from yahoo answers:

Link:   http://answers.yahoo.com/question/index?qid=20090115192825AAvub4R

Post:    Can I put my razr sim card into an unlocked iphone 3g?

• Answerer 2:  you can, but you would need to get an internet/data plan. that is mandatory with the iphone because the internet is on all the time (that's why it opens so quickly) so you would get outrageous charges if you didn't have it.

I'm pretty confident that you need to jailbreak and unlock the iPhone in order to use without data plan. But question bubbles whether it works with 3G or not. Google it and you sure will get an answer and get the firmware (One of my friends did the same: bought iPhone online and is using existing ATT simcard). ATT won't be able to find out that you are using iPhone. It takes just like 5 mins to jailbreak and unlock.

thanks rata makai

can i unlock a 3GS using some free software? I got a good deal on a locked one. Which software did your friend use and how did he do it? Can you please give details?

U cant avoid data charge which is $30.00. Before November of 2009, you could have done so, but now it is mandatory that if you carry any sort of smart phone you will require to have data plan, if not then u will be asked to get any other phone. You have no choice, I am just being honest. Iphone line cha bahne be prepared for data plan charges every month. Regularly, other regular ph ma you can login to the att website and change ur plans or features as desired, but if you have a smart ph, u cant change it at all. Even, if you get to a point where u can remove the data plan, within next hour the ph will be automatically detected and thus data plan will be added by itself again. No matter how many managers u will talk to, u will still have to pay for data plan. sala haru khaye kha na khaye ghich abhiyan ma lageko chan. its due to iphone all other smart phs ma pani yehi mandatory rule lagako cha. Not only at&t, its similar with all other carriers sadly. Before cell ph carriers were more focused on making money on minutes, now they are after data usages. Imagine the popularity of smart phone these days? now think abt this, how much revenue they can generate with this mandatory $30 rule with millions of customer. aaru regular ph ma pani, yesari banako huncha ki jhukkera u will click on internet. ek khep connect huna saath minimum i guess $1.99 charge huncha hola, but there u can opt out internet.. jailbreak garda ph detect hundaina bhane chahi story pharak cha, jasle recently jailbreak garera chalako cha uslai sodhnu parcha hola yo kura. share garum alikati information yeta . 

1. u dont have to unlock an iphone to use another AT&T sim card.
2. just make sure ur sim card has a fiery ball with 3G symbol on it.
3. dont let ATT know that u gonna use iPhone.
4. call csr and tell them u want to put datablock soc code on ur number. datablock will block internet.
5. they will scare u by saying that iphone automatically updates itself so u gonna accrue more $$ charges if u dont get dataplan. that is totally false. u can disable automatic update in ur iphone to avoid that.,
whatever dharane kancha said is  true.. thts how an att rep will "educate" u if u sonsult with them.
6. they will know u r using iphone only if u give them ur iphone IMEI number. with iphone IMEI no, AT&T's software mandates dataplan so use ur Raz IMEI, or in other words, as i said earlier, dont "update" imei in their system.
7. AT&T follows the moto " Customer is always right" so.. even if their system detects iphone and sends u sms.... u can disregard it.. or actually call them and tell them tht they are harrassign u by sending iphone alert messages in ur moto razor phone. to be on the safe side, put ur sim in moto raz when u call them.

dharane_kancha;

thanks ratamakai for taking the time to try to ask your friend. Let us know when you find sth.

Hi mohanB,
  Don't rely on software's and tools to unlock your Iphone3GS  because I have heard many got their phones bricked by using the tools.So you can  approach your network provider to unlock your Iphone3GS If they denied use  remote unlocking service from http://www.mobileunlocksolutions.com/apple-iphone-3gs/rs16wp9/ and unlock your iphone from the respective locked network.

Technically you can't avoid data plan if you gonna use smartphone on ATT. Whether you provide them IMEI number or not, their system will automatically detect the phone and IEMI number once you swap your sim card into smart phone. You can avoid being detected if you use smartphone purchased from country other than USA. They have all the IMEI numbers of the smartphones sold in USA. That said, you can still use a smartphone and take a chance. I have been using smartphone on ATT since last two years and they have added data plan thrice in between. Whenever they added dataplan, I swapped sim card back to the old feature phone and called them to remove the data. Its working so far.

@PEPSI.. I didn't realize year associated with th the thread.
I only noticed may 30. Damn Yellowflower who bumped this thread and made me look like a fool.

@[Disallowed String for - excessive promotions]DOTcom

I am getting banned for excessive promotions.