If you live in Europe, Australia or New Zealand you can bring your own GMS mobile. The Czech Republic uses the GMS 900 system. Now there is also a new networks allowing use of 3G phones. It is recommended though that you check with your mobile provider before you leave about using your phone in Prague. If you are planning a longer stay it may be worth buying or renting a phone as calls made via roaming tend to be very expensive (but at least it is much cheaper then it used to be due to the EU regualtions). There are three major mobile phone operators. O2 (before Eurotel), T-Mobile and Vodafone (before Oskar). Calls made from Czech mobiles to mobiles or landlines cost between 3 CZK to 9 CZK per minute. You can buy a prepaid phone from around 1500 CZK or you can buy a sim card and use it with your existing mobile phone. Mobiles phones in Prague are very common, and probably more then 85% of the population use theirs every day, and for those text addicts - you can send a free sms message to Eurotel or Oskar users from their www pages. If you coming to Prague from UK some operators allow use you allowence (your free minutes) even in you are abrod, check it before you fly.