If you have bought an iPlum phone number, we are passing your iPlum number in the Caller ID section of the call as per global E.164 standards.
When you call any North America number or in most parts of the world, your iPlum number would show up as Caller-ID. But in some countries certain local carriers may change that number in the packet header & insert a local numbers due to local regulations when they terminate the call at the end-user side.