What are SIP numbers? Do they belong to any country?
SIP numbers are also called virtual, or international numbers. These are 15-digit endpoints identified by numbers starting from +883140.
They are not dedicated to a single country.
Virtual (international) numbers are treated by Apifonica REST API as conventional telephone numbers. These numbers have all the same properties as conventional phone numbers except for they use SIP protocol to connect.
The only important thing about virtual numbers is that virtual numbers cannot be called from fixed or mobile numbers.