Here are some more information for Dual Modems:

The Cell Phone Mysteries, What Are Dual Band, Tri Band And Quad Band Cell Phones And Where Will They Work?

The world of the mobile phone is a confusing one these days, particularly for those wondering how to start a cell phone business. Few things are perhaps as confusing as GSM frequencies and GSM phones that seem to work in some parts of the world but not in others.

Multiple band cell phones and GSM frequencies can be especially confusing for anyone wondering how to start a cell phone business.

So what is the background behind the GSM network?

The GSM network was first suggested by a group of European technicians and policy makers in 1982 and it didn't take long for consumers and phone makers to adopt the new network after it first emerged in 1991. It wasn't long before there was growing GSM coverage in an increasing number of countries.

The GSM world grew quickly. There were more than one million subscribers spread over 70 carriers in 30 countries by the end of 1993.

Not only did the new GSM mobile network send and receive all of its information digitally, making it the first 2G mobile phone to be developed it also gave users a great deal of freedom on what they did with it. For the first time they were able to send short written messages to each other for a fraction of the price of a phone call, they could change their carrier and/or go to a different country without getting a new phone.

All they needed to do was to take one GSM SIM card out and replace it with another GSM card and they were in business.

But, as the unknown powers of the world decree, things shouldn't be that easy and the GSM frequencies set by most of the GSM networks had already been assigned to other purposes by the powers that be.

So, in a situation very similar to TV watchers and people with surveillance systems, a phone that worked in Sussex England wouldn't pick up anything in San Antonio in the US. Basically it wasn't a case of one GSM frequency fits all.

As a result, many cell phone makers create cell phones that can work with more than one band with some working with as many as 4 bands.

Still this doesn't mean there aren't questions and people are often left asking:

* What is GSM?

* What are the GSM frequencies?

* Why do GSM phones have more than one band?

* Will different frequencies work in different areas?

* How can I check if a phone will work in a particular area?

* How are multiple band phones defined and where will they work?

We're going to attempt to look at those questions in this article.

What is GSM?

GSM, Global System for Mobile communications (or the Acronym formally known as Groupe Spécial Mobile) is a wireless transmission standard used for mobile phones and, recently wireless modems. GSM and CDMA differ because GSM networks use a SIM card to store all the necessary information to send and receive calls where with CDMA phones everything is kept on the phones.

If you are looking at how to start a cell phone business and you don't have thousands in working capital GSM mobile phones will probably be a better option than CDMA as they won't be attached to a particular carrier and don't require you to be licensed to a particular provider to sell unlocked cell phones.

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, Cell phones wholesalers make GSM and GPRS phones with multiple cell phone bands so that they can work in multip 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.

If you are looking for a GSM world phone that will work in the US or South America then you're better sticking with a wireless cell phone that'll work on the 850Mhz and 1900MHz bands.

Will different frequencies work in different areas?

With the majority of the GSM world being broken into two main groups (those that take Most of the GSM world is roughly broken up into four main frequencies 900MHz and/or 1800MHz and 850Mhz and/or 1900MHz most unlocked GSM phones will work on one, two or three of the GSM frequencies around the world giving you some level of international roaming on an unlocked phone.

However, you possibly won't get any joy if for example you take a dual band phone designed for Europe and Asia and then try to use that bluetooth phone in the US.

How can I check if a phone will work in a particular area?

There are two ways to check if a phone will work in a particular area; the first is to get the phone band, which can usually be found on the product description.

If you're working through how to start a cell phone business and considering phones to stock, it doesn't matter if you're thinking about a multimedia mobile, WAP phone or GSM watch phone, the process should be the same. If you are sourcing cell phones from a wholesale supplier or wholesale dropship vendor put the ball into their court. They should have that information on their website or product advertising material for the unlocked cell phone.

Once you've got the GSM frequency the GSM phone worked on you can make sure it will work in your area.

About the Author

Sogoya.com is a b2c Platform, an online electronics wholesale and Retail Company registered in China. we offer you factory-direct pricing with a rapid delivery time, We buy the very latest consumer electronics products from suppliers in China and make them available to you at unbeatable wholesale price. This is the best opportunity to buy direct from China!

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