I could be wrong, but I have a wild guess that both voxalot accounts you used to do the test are yours. You simply exported/imported the accout setting to set up the other account. However, in this situation, the VoSP passwords were not exported/imported. You need to enter the voipdiscount password manually in the other voxalot account. That's why you get the strange thing that you can dial other voxalot user and *500, *600, but not any real PSTN number.