Please Pay attention to INT Service Details:
This is an intelligent, symmetric and two-way service, using this service, not only you can call Tehran landline, but also you can receive calls from Iran too.
it is a monthly and will be renewed every 30 days.
There is no hidden fee, no connection fee.
This service is unlimited but there is a Fair usage Policy as a home user.
Monthly cost of this service 19.90 USD + 4.00 USD (Tax & surcharge) .
Be advised there is no other company offering unlimited call to Iran at the present.