You can call to fixed or mobile numbers even when your account balance is empty. The Interest-Free Credit service is available to every permanent user of SIPNET. The service is active for 7 days.
The amount of available credit is calculated individually for each user. It is equivalent to 5% of the total amount uploaded to the user's SIPNET account over the past six months.
For example, if you have spent 100 USD on long-distance and international calls over the past six months, you can get 5 USD in credit.