Before you can make a call, your first need to sign up with a provider. (or connect to your office PBX).
A list with popular providers in your area can be found here:
I can call some international countries, but other countries do not work.
If you can call some international destinations, but others do not work, please contact your provider for assistance. It is possible that extra destinations require unblocking on their end.
Calling national destinations works, but international destinations do not work.
When you already have a provider configured in Zoiper, but an error is shown when trying to call a certain destination, please ensure the international prefix is correct.
Some providers will require international numbers to start with the international call prefix +, others will require 00, 011, 010, 0011 or other prefixes, followed by the country code. ( a complete with all country codes can be found here )
Please contact your provider for more information on how to form international numbers.
More information on the possible prefixes can be found here:
Zoiper can automatically add or change the international call prefix and add the country code if required.