Zoiper can not be found in the BlackBerry World store, or in the Amazon Appstore.
The only way how you are able to get Zoiper on Blackberry is if you contact us at firstname.lastname@example.org; we will send you a custom link, from which you will be able to download the necessary .apk file and install Zoiper on your BlackBerry device. Keep in mind that this would work with Zoiper "1.0" (legacy product) for Android on your Blackberry OS device.
If you are using an Android-based Blackberry device, then you can use Zoiper "2.0" on it. Contact us at email@example.com for instructions, or if you have access to Google Play Store - just search and download it from there.