For all new Plivo accounts, only US and Canada are geo-enabled for calling. Calls made to other destination countries will fail with hangup - Destination Country Barred.
You can modify the country permissions under Voice > Geo Permissions on the Plivo console. This is a security feature. Carefully enable the countries where you intend to make calls and keep the rest of the countries disabled.
For more information on voice geo-permissions, please visit the dedicated FAQ section.