Another reason to select GSM over CDMA is that it will open up the potential customer base for each phone. As unlocked gsm phones can be used with any GSM networks. To date there is no such thing as an unlocked CDMA phone. When it comes to cell phone plans most providers (especially those in the states) love CDMA phones because it locks their consumers to them.
Why do GSM phones have more than one band? GSM Phones come with more than one band so that they will work in more than one country as there is more than one GSM frequency and they are not universally transmitted.
As a result, wholesale cellphone manufacturers make GSM and GPRS phones with multiple cell phone bands so that they can work in multiple countries. Most cell phones work on two, three or even four bands. Quad band phones are the most flexible as they can be used all over the world and are often called international phones as a result.
How are multiple band phones defined and where will they work? Multiple band phones are usually defined by how many GSM frequencies they can operate on and usually come in four different categories, dual band, tri band and quad band. If thinking about how to start a cell phone business it is important to remember the different type of bands as it could mean the difference between your customer getting a high performance phone that they're happy with and can and them getting a shiny and costly paperweight.
Dual band phone works with two GSM frequencies and, depending on where the phone is made will probably work for the frequencies 900MHz and 1800MHz. These phones are usually less expensive than other types of cell phone and it can be a good way to get a cheap cell phone that will still send SMS MMS and act as a WAP cell phone.
The tri band phone runs on three frequencies and can be used in most countries. This unlocked GSM cell phone is a cheaper option than the quad band phone but safer than a dual band phone.
Quad band phones, or international phones as they are sometimes called, use four bands and can be used anywhere in the world. If you are looking to start a mobile phone business and you wonder what is an unlocked phone guaranteed to sell well and give you the least trouble with customers it will probably be this type of cellphone.
What Are The GSM Frequencies? Almost all of the world works on the frequencies 850Mhz, 900MHz, 1800MHz, 1900Mhz and in some rare circumstances 400MHz although there are some other frequencies in other locations.
Thankfully too areas where each frequencies work is fairly easy to define in the very general sense (although it always pays to check). So when you're looking for what areas a cellular phone will work in you should be able to follow a rough guide.
So which areas use GSM 900 and 1800 MHZ signals and which areas use the GSM 850Mhz and 1900MHz frequencies can usually be broken into two groups.
If you are traveling in with your cell phone in Oceania, Africa, Europe, Asia (except for Japan and Korea), the Middle East, Brazil and the Baltic region and looking for roaming networks then mobile network coverage will be either 900MHz, 1800MHz or 900MHz and 1800MHz.
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