Because I was looking for a new mobile phone I delve into the various frequencies of the mobile phone and where you can use it when you buy one.
I found the following information on two websites, from Knowhow.com and Calibryze.com.
This information is more focused on the U.S. mobile network than on the Dutch network but there is a good explanation about all frequencies and where to use your mobile globally.
I hope you can use this information.

What is a mobile phone strap and what are the differences between dual-, tri-, quad-and penta-band phones?

The mobile phone you use will be either dual-, tri-, quad-, or penta- band.
Mobile handsets use different radio signals (bands) to make and receive calls, and some handsets can pick up more signals than others.
This article looks at the different bands, and explains why a multiple-band mobile is the best option for international travel.

 

The Knowhow

Mobile frequencies (bands) vary between countries.
Most modern handsets can pick up more than one frequency, so they can be used in more than one location around the world.

The names dual, tri, quad and penta refer to mobiles which can pick up more than one band.
Multi-band mobiles are more flexible, and the better signal coverage they offer makes them a good choice of handset for those who regularly travel abroad.

 What is a mobile band?

       The difference between dual, tri, quad, and penta-band mobiles

  CONNECTION COVERAGE  
DUAL-BAND A dual-band mobile connects to two different bands For GSM 850-1900 phones: The Americas For GSM 900-1800 phones: Europe, Africa, Asia, Brazil
TRI-BAND A tri-band handset connects to 3 bands European tri-band: Europe & the Americas North American tri-band: extensive coverage throughout the Americas, with limited reception elsewhere
QUAD-BAND A quad-band handset connects to 4 bands Can be used almost anywhere worldwide, except Japan & South Korea (unless you have a 3G quad-band phone) They cannot be used in Burma, Monserrat, or Myanmar
PENTA-BAND A penta-band phone can use 5 bands Penta-band mobiles support 2G & 3G (which means they can be used in Japan and South Korea) They cannot be used in Burma, Monserrat, or Myanmar

Information above comes from Knowhow.com

Information down below comes from Calibryze.com

GSM Mobile Phone Coverage Information

This page explains a bit about GSM phones, in overall terms, in order to help you decide whether a dual-band, tri-band or quad-band phone will best meet your needs.  
Generally, tri-band or quad-band GSM phones will work in most places in the world.  
Dual-band phones, however, are available in two varieties.
The most common type of dual-band phones will work in Europe and Asia. But in the USA, Canada, other parts of the Americas, some of Asia, and elsewhere, you'll need a specifiic kind of dual-band phone intended for those countries.  
We've included lists of countries below to help clear up which type of phone will work where.

Note that even where tri-band phones are supported, such as in the USA, you may not have a signal in as many places as you would with a quad-band phone.  
You can check your service provider's website, or contact their customer support for more information about the extent of their coverage on each frequency band.

What is GSM anyway, and what's all this about dual-band, tri-band, and quad-band?

GSM stands for "Global System for Mobile communications".  
In the simplest terms, it's a "language" that mobile phones use to communicate.  
It's by far the most common language worldwide...however not all mobile phones are GSM phones.
Whether you need a GSM phone depends on which service provider you sign up with.  
In the USA, for instance AT&T / Cingular and T-Mobile generally require you to have a GSM phone, while Verizon requires you to have a phone that speaks a different language called CDMA.  
With very few exceptions, a phone that works with AT&T or T-Mobile's networks in the USA will NOT work with Verizon's network, and vice-versa.

It would be that simple, except that different countries require mobile phones to communicate on different frequencies.  
Hence there are different types of GSM phones that can communicate on some, but not all, GSM frequencies.  
Almost all GSM phones fall into 4 categories: North American dual-band, Europe/Asia dual-band, tri-band, and quad-band.  
Dual-band
phones can communicate on two particular frequencies, tri-band on three, and quad-band on all four.

This doesn't mean that a quad-band phone is "better", or sounds any different than a dual-band phone...just that the quad-band phone can connect to more networks in more parts of the world.
If you plan to travel to countries that use different frequencies than your home country, you may consider getting a tri-band or quad-band phone that can be used in both places.  
The lists of countries below are intended to help you decide what type of phone you need, depending on where you plan to use it.

How do I know whether my phone is dual-band, tri-band, and quad-band?

Unfortunately GSM phones usually don't offer any easy way to tell which bands they support just by looking at them.  
Many models also come in slightly different varieties for different parts of the world.  
The user's manual may tell you, or you may have to search for your phone's model number online...or you may have to check with whoever you purchased it from.

What's a "locked" or "unlocked" phone?

So, just because you buy the right type of phone for the network and country where you plan to use it, doesn't mean it will work.  
Mobile phone networks in many countries have made it more complicated.  
They've decided they only want you to use the phone that you bought from them on THEIR network.  
So, they sell phones that are "locked" to their network and cannot be used on anyone else's network, unless you can "unlock" it (there are those who will unlock your phone, for a fee).  
So when buying a GSM phone, you have to make sure it's either unlocked before you buy it, or locked to the specific network (Cingular, T-Mobile etc.) that you plan to use.

An unlocked phone is preferable, since you're free to use it wherever you like, you can keep it if you switch networks, and you can sell it to anyone else (not just to someone on the same network as you).  

What's 3G?  How do I use it?

3G is the umbrella term for the newer "third generation" of wireless communication networks, which are still in the process of being implemented in many places.  
The idea of 3G is to bring multimedia and broadband Internet to mobile phones.  
It lets you to do things like make 2-way video calls, watch TV shows and video clips, and surf the Internet at high speeds on your phone, PDA, or notebook.  
In order to use it, you must have a 3G-compatible device, and use a provider with a 3G network in place where you're calling from.  
Of course, the provider will usually charge extra for all of these multimedia services.

Most 3G phones will still allow you to make phone calls on regular GSM networks if no 3G service is available.  
Most 3G phones are tri-band or quad-band, and will work in the countries listed below where those bands are supported.  

The following are some lists of countries where various GSM phones should work, and where they won't work.

We can make no guarantee that the following information is complete or accurate.

All GSM phones except North American dual-band phones:

These countries & territories use, at minimum, GSM 900 and/or 1800 frequencies.  
Quad-band, tri-band and Europe/Asia dual-band phones should work in these countries.  
North American dual-band phones generally WILL NOT work here:

  • Albania
  • Algeria
  • Andorra
  • Angola
  • Antigua
  • Antilles
  • Armenia
  • Aruba
  • Australia
  • Austria
  • Azerbaijan
  • Bahrain
  • Bangladesh
  • Barbados
  • Afghanistan
  • Barbuda
  • Belarus
  • Belgium
  • Benin
  • Bhutan
  • Bosnia
  • Botswana
  • Brazil
  • British Virgin Islands
  • Brunei Darussalam
  • Bulgaria
  • Burkina Faso
  • Burundi
  • Cambodia
  • Cameroon
  • Cape Verde
  • Central African Republic
  • Chad
  • China
  • Democratic Republic of the Congo
  • Cook Islands
  • Costa Rica
  • Ivory Coast
  • Croatia
  • Cuba
  • Cyprus
  • Czech Republic
  • Denmark
  • Djibouti
  • Dominica
     
  • Dominican Republic
     
  • East Timor
  • Egypt
  • El Salvador
  • Equatorial Guinea
  • Eritrea
  • Estonia
  • Ethiopia
  • Falkland Islands
  • Faroe Islands
  • Fiji
  • Finland
  • France
  • French Guiana
  • French Polynesia
  • French West Indies
  • Gabon
  • Gambia
  • Georgia (the country!)
  • Germany
  • Ghana
  • Gibraltar
  • Greece
  • Greenland
  • Grenada
  • Grenadines
  • Guadeloupe
  • Guatemala
  • Guernsey
  • Guinea
  • Guinea-Bissau
  • Guyana
  • Herzegovina
  • Hong Kong
  • Hungary
  • Iceland
  • India
  • Indonesia
  • Iran
  • Iraq
  • Ireland
  • Islas Malvinas
  • Isle of Man
  • Israel
  • Italy
  • Jamaica
  • Jersey (the country!)
  • Jordan
  • Kazakhstan
  • Kenya
  • Kiribati
  • Kuwait
  • Kyrgyzstan
  • Laos
  • Latvia
  • Lebanon
  • Lesotho
  • Liberia
  • Libya
  • Liechtenstein
  • Lithuania
  • Luxembourg
  • Macau
  • Macedonia
  • Madagascar
  • Malawi
  • Malaysia
  • Maldives
  • Mali
  • Malta
  • Martinique
  • Mauritania
  • Mauritius
  • Micronesia
  • Miquelon
  • Moldova
  • Monaco
  • Mongolia
  • Montenegro
  • Morocco
  • Mozambique
  • Namibia
  • Nepal
  • Netherlands
  • Nevis Island
  • New Caledonia
  • New Zealand
  • Niger
  • Nigeria
  • North Korea
  • Norway
  • Oman
  • Pakistan
  • Palau
  • Palestine
  • Papua New Guinea
  • Philippines
  • Poland
  • Portugal
  • Principe
  • Qatar
  • Reunion
  • Romania
  • Russia
  • Rwanda
  • Saint Kitts
  • Saint Lucia
  • Saint Pierre
  • Saint Vincent
  • Samoa
  • San Marino
  • Sao Tome
  • Saudi Arabia
  • Senegal
  • Serbia
  • Seychelles
  • Sierra Leone
  • Singapore
  • Slovakia
  • Slovenia
  • Solomon Islands
  • Somalia
  • South Africa
  • Spain
  • Sri Lanka
  • Sudan
  • Suriname
  • Swaziland
  • Sweden
  • Switzerland
  • Syria
  • Taiwan
  • Tajikistan
  • Tanzania
  • Thailand
  • Timor-Leste
  • Tobago
  • Togo
  • Tonga
  • Trinidad
  • Tunisia
  • Turkey
  • Turkmenistan
  • Uganda
  • Ukraine
  • United Arab Emirates
  • United Kingdom
  • Uruguay
  • Uzbekistan
  • Vanatu
  • Venezuela
  • Vietnam
  • Yemen
  • Zambia
  • Zimbabwe

All GSM phones except Europe/Asia dual-band phones:

These countries / territories use only GSM 850 and/or GSM 1900 frequencies, so only quad-band, tri-band and North American dual-band GSM phones should work.  
Europe/Asia dual-band phones WILL NOT work here:

  • Anguilla
  • Argentina
  • Bahamas
  • Belize
  • Bermuda
  • Bolivia
  • Canada
  • Cayman Islands
  • Chile
  • Colombia
  • Ecuador
  • Guam
  • Honduras
  • Mexico
  • Nicaragua
  • Northern Mariana Islands
  • Paraguay
  • Peru
  • Puerto Rico
  • United States of America
  • U.S. Virgin Islands

 

Quad-band & North American dual-band GSM phones only:

A couple of countries use only the GSM 850 frequency, so only quad-band phones and North American dual-band / tri-band phones will work.  
Europe/Asia dual-band and tri-band phones WILL NOT work here:

  • Montserrat
  • Panama

 

All GSM phones:

A few places use all four GSM frequencies.  
Depending on which network you plan to use, any GSM phone should work here:

  • Caicos Islands
  • Haiti
  • Turks Islands

 

3G phones only:

These countries / territories use 3G service only.  
A 3G-capable phone is required. Quad-band, tri-band and dual-band GSM phones WILL NOT work unless they also support 3G:

  • Japan
  • South Korea

 

No service:

These countries / territories have no GSM service whatsoever, or networks are still in the process of being rolled out.  
Until services are in place, NO GSM phones will work (dual-band, tri-band or quad-band):

  • Myanmar / Burma
  • Comoros

 

We can't guarantee that this information is complete or accurate.