There is no possibility to register to this type of applications. You will need to buy a local pre-paid card. On the back of the card there are printed username and password, as well as the operator code you have to use when connecting. GulfDial and similar applications use a VoIP server to connect in order to place calls. If you have any questions about the software or want to find more about resellers, access the official website and scroll down until you see the contact form. Send them an email and you will get your response.
