To be able to understand, let us look into the GSM classifications very briefly.
Global System for Mobile Communications (GSM), is a world leading standard, first adopted in The european countries and then spread through Asia, Africa and Down under, New Zealand, and so forth GSM coverage maps are around for almost all courtiers. This can be a digital technology and uses Period Division Multiplexing methods in communication. There are 3 kinds of GSM phones that are available: more information
The dual band GSM phones operate on 900MHz or 1800MHz. These phones will not work with the companies operating on 850MHz.
The tri-band phones have working frequencies of 900MHz, 1800MHz and 1900MHz bands. These types of phones will work around the world including North America, but will not work in places where the providers support only 850MHz.
The quad strap phones, one the other side of the lieu hand, operates on 850MHz, 900MHz, 1800MHz, and 1900MHZ and therefore would work every where throughout the world with all the service providers.
Consequently, for your international travel, it is necessary that your GSM mobile is a quad band handset for it to work world-wide. Or perhaps else, it may atleast support tri-band frequency ranges. If perhaps you do not own such a phone, you can always rent one for your travel overseas. Please visit http://www.planetomni.com/RENT_INFO.shtml for more information.
A pre-paid SIM card activates your GSM mobile, without you having to enter into any contract with the provider. It already has airtime credit included in it, upon purchasing such a card. If you have come to the limit of your airtime credit, you could re-charge the card with re-charge vouchers, to extend your credit. The SIM greeting card has a life course of 6 months, after which a you need to get a new Sim. With some service providers, this life span of the SIM card can be increased indefinitely keeping on recharging the cards for your airtime credit.
Together with the pre-paid global SIM card, you get the benefit for having the same number, which you can carry through your voyage in various parts of the earth. On top of that, the calls you get are free of cost, regardless of where it is produced from. You save on the charges that you would need to pay for roaming, which you have incurred, if you would probably take your common mobile with you. Even more, it is doubtful whether your phone would work in the countries you visit, if you do not have a quad band handset. In this scenario, imagine the charges that you would pay to call your business associates or your family at home, from your hotel room. A pre-paid global roaming SIM greeting card has that much cutting down for you.
So what do you generally get with your prepaid global roaming SIM card?
A starter airtime credit.
Cost-free incoming calls.
All fun loving calls at local rate.
No roaming charge for international calls.
International walking around in over 100 countries.
A phone number which you can bring any part of the world.
Free incoming SMS.