To send SMS campaigns internationally you need to ensure that the mobile number includes the country code, and that Address 1 Country field is populated corresponding to the country code of the contact's mobile number.
For example, sending to a mobile in the United States (+1), a number such as +1(555)123-4567 should read as:
+15551234567
The country field must match one of the below:
Australia
Austria
Belgium
Britain
Croatia
Czech Republic
Denmark
England
Finland
France
Germany
Great Britain
Greece
Guernsey
Iceland
Isle of Man
Italy
Jersey
Luxembourg
Malta
Netherlands
Northern Ireland
Norway
Poland
Portugal
Republic of Ireland
Romania
Scotland
Spain
U.K
U.S.A
UK
United Kingdom
United States
Wales
Countries with restrictions:
US will need a Toll-free number
Australia will require Sender Id registration
Costs
For the US there is a monthly rental of £25 for the line in addition to the credits
For the UK are sent at single credits
For Germany, France, Italy and Spain have a cost of 2x credits
For all other countries it is 1.5x credits