Compatibility questions before arriving to the US
 

I’ll be traveling in New York, Los Angeles and Las Vegas next month.
I have an unlocked Samsung Galaxy S i9000 phone which supports:
GSM 850 / 900 / 1800 / 1900
HSDPA 900 / 1900 / 2100

I want to get a prepaid SIM card for local and long distance calls, but will also want to use it for data.
I don't know yet which one I'll be going with, but by reading the threads here, I understand that T mobile uses mostly 1700 for 3g and AT&T uses mostly 850 for 3g. Thus, I guess I will not have any problems with voice calls, but since my phone doesn’t support both these 3g frequencies, browsing and emailing will be only on 2g.
1. Am I correct – no problems with voice calls, but slow data? (with both T mobile and AT&T)
2. I will need the internet mostly for emails and entering websites of hotels and flight booking. Will the 2g data be sufficient for that?
Thanks

Continuing my last questions, I thought I could get this usb 3g modem which supports UMTS 2100/1900/850 - http://www.amazon.com/Huawei-E1556-U...6311667&sr=8-1

Can I get a SIM card from AT&T, stick it in my phone for voice calls, and when I need to use the internet, put it in this USB modem which supports 850MHZ in 3g, and browse with my laptop?

Is this even possible, Using a regular SIM card with this type of modem?

Can AT&T deny data usage if I try to use the SIM card with a modem and not with a phone?

The UMTS "2100" & "1700" designation is confusing. It's better to speak in terms of the UMTS Frequency Bands. Currently AT&T uses Bands II & V. T-Mobile uses only Band IV. Which band AT&T uses in a given area depends mostly on which frequencies they had the most of in that license area. So, you may find that having Band II (1900) will provide service in some areas but not in others.

AT&T is pretty picky about tethering or using a data stick without a special, expensive data plan. They watch traffic patterns to detect this. If you plan to do this I suggest you set up a VPN server, preferably answering on a HTTPS port. So it looks like you're just doing a lot of HTTPS surfing.

Thanks for the quick reply.
Am I correct that by using this phone with either a T mobile or AT&T SIM card I will have no problems with voice calls?

Setting up a VPN server - should this be done on my PC? Could you please explain or refer me to a link that might explain how this should be done?

Thanks for helping

I just bought this one last week and it works fine with my AT&T and tmobile sims.

AT&T Unlocked Sierra USBConnect 308 Shockwave 4G HSPA+ USB Modem w/ MicroSD Slot | eBay

Specs - AT&T Wireless- Device Specifications of the AT&T USBConnect Shockwave (USB 308

Thanks,

Is T-mobile less restrictive than AT&T regarding their data usage policy?
Meaning, if i get a T mobile compatible usb modem, will there be any problems using the prepaid sim and a regular pay as you go plan, to browse the internet with it?

And again, just to make sure, will I be able to use my phone with a Tmobile SIM for voice calls and texts?

A VPN server can be set up on your PC or on your router running a 3rd party firmware, such as DD-WRT. At this time I'm not familiar with the current policies of AT&T and T-Mobile wrt prepaid data.

Just wanted to update that I just returned from the US.
I purchased an AT&T prepaid sim card.
For my surprise, while in big cities (NY,LA,Vegas) I was always connected with HSDPA and had fast internet Data connection.
When traveled to isolated areas, only EDGE connection was available.

Although most of my internet usage was done using the phone, I had no problem with tethering when needed to use my laptop.