There are a couple of ways to call a Kaldan number for free. This page will assume that you do not have a Kaldan telephone number, nor will you be interested in paying for one. Since the telephone network is SIP based, it would be able to use tried and true protocols that would also work not only for terrestrial telephones, but cellular phones as well. Knowing that the network is SIP based is important as both options relies on this fact.
The first way requires that your phone provider supports dialing SIP addresses. For some reason, not all SIP providers does this. When one wishes to call you via SIP, they will enter sip:domestc-kaldan-number@tel.ka. This will allow anyone in the world to have the opportunity to reach out. The caller ID display will show the SIP address of the caller. The second option is to use SIP Broker. As with Kaldus attempting to acquire the +883 country code, Kaldus will also attempt to acquire *883 for SIP Broker calls. This will make things as easy to remember as possible. In which case, the person calling will need to dial their providers SIP Broker code followed by *883 domestc-kaldan-number. As with calling from a SIP address, the caller ID will show the SIP address that is calling rather than a telephone number.
You can choose to disable receiving SIP calls. This could reduce the chance of SPAM, especially as one might learn how easy it would be to call a Kaldan telephone number for free. It would just make sense to allow the subscriber to disable this feature. To make outgoing SIP calls, there must be a SIP client in place, or the use of SIP Broker. When calling using SIP Broker, one will prepend the SIP Broker number with 111, and drop the preceding *.