Pls help !!!

[vatana]

Hi All !

I have a question could anybody answer me. Thanks alots.

I see on the website that all world phone or phone in USA work with GSM 850/1800/1900. Can it be used in Asia Pacific with GSM 900/1800/1900 ? What is difference betweent GSM850 and GSM 900 ? I asked my network provider here thay said that only phone above 900 ???

BR,
Vatana

[Thanh]

Dear Nam :)
Thanks for your PM, i replied. I can answer your question here, too :)
GSM is "Global System for Mobile communication" and a digital voice and data transmission standard.
The number behind GSM (850, 900, 1800 and 1900) tell you on which frequency this is used.
Mobile phones are in fact radio transmitters and receivers, and same as your FM stereo, they need specific frequencies to work on. Now, GSM as such may be the same in all the world, but some network providers use other frequencies than others.
In Northern america, the used frequencies are around 850 MHz and 1900 MHz for GSM, while most of the rest of the worl is using 900 MHz or 1800 MHz. If you have a "Tri-Band-Phone", this can work on the frequencies 900, 1800 and 1900. American "Dual Band Phones" work on 850 and 1900, other "Dual Band Phones" work on 900 and 1800.
Here in Thailand GSM is used in all three ranges, being AIS with 900, Hello, Orange and D-Tac on 1800 and Suthep (Thai Mobile) on 1900.
In your country there is used 900 and 1800 as well as CDMA, which is another standard, not GSM.
So you can NOT use an american GSM dual band phone in your country, while here in Thailand you could only use it on Suthep, which covers only inner Bangkok with it's relatively new network. Even a tri-band from america won't help you as in VN there is no 1900 network.
I hope i could answer your question......
Kindest regards.....
your Thanh