The cost of calling
In order to be able to use your mobile phone in Denmark, your normal provider will need to have a roaming agreement with one of the Danish mobile phone operators. This is normal practice but it is a good idea to check both the availability and cost before you travel, as it can be quite pricey depending on where you're from or where you're calling.
Visit the European Commission website for the latest, up-to-date information on roaming tariffs in Europe.
Danish phone numbers normally consists of 8 digits. The Danish country calling code is +45 which should be added before the number in order to call a Danish number from the UK.