Is Wifi Data Abroad Free?

After reading many threads, I don't really have clear answer to my question.

Will be traveling in a few months to Mexico for 1 week from the US, and I would like to use the my BB Bold 9700 only for bbm, internet, emails, and some apps llike FB, but I don't want to incur any charges whatsoever.

So based on my understanding from what I've read, if I set the BB under manage connections, uncheck the mobile network (I have AT&T) and check off wi-fi. Then under mobile network options, data services - on, but when roaming - off. Then on the internet browser options, change the browser from internet browser to hotspot browser, then the Wifi Data is enabled and will work outside of the US and in another country wherever there is wifi available. However, let's say if the wifi hotspot is free in the other country, can anyone verify if there will be any data usage or roaming charges for the data since "Data Services" is on and being used outside the US with all the above mentioned settings for the BB?

If there are charges, then is there any way to get around using the BB to access anything out of the US without incurring any additional charges than what the normal billing is for an AT&T customer?

Thanks

Talk to AT&T. I know with T-mo you can use any wifi anywhere in the world and it counts as you BIS or minutes come out of your normal plan using UMA. No roaming charges or anything.

im not sure about the wifi setup but you cant use wifi to access bbm, that strictly a BIS thing

The wifi does work to access bbm, using those same settings I described above, and this being I'm still within the US. I tried it this morning and spoke to my friends fine.

Anyone have definitive answer to this question? I am interested to know the answer myself. This is one of those things that I can't test myself, as a fail could be quite expense before I had any idea.

Thanks.