I talked to CC. New plans that have unlimited calling, no additional rental is applicable. For old plans that do not have unlimited calling, additional 99 rental is applicable.
There are 2 conditions to continue unlimited free calls offer:
a. In a week, there must not be more than 300 distinct dialled numbers.
b. In a week, it is must to have incoming calls of minimum 15 min duration.
There is no limit on number of minutes for local/std. No 5000 min limit.