Sql server full text search performance with additional conditions
Kin made a couple of suggestions which should be helpful.

First: Make sure that your statistics for the CallTime index are up to date.

Your plan shows that the time filter is being made by seeks to the clustered index.  So, for some reason the CallTime index is not being used.  What is the definition of that index?  If it is a multicolumn index, be sure that the most specific column is first. Example:

IDX_Calls_CallTime
  NOT: CallID, CallTime
  USE: CallTime, CallID


Second: Consider using CONTAINSTABLE.

I doubt that you will ever want to return 1.200.000 rows for "efendim".  By using CONTAINSTABLE and ranking you can set the top number of rows that you want, thus reducing the number of FullText results to process to 10, 100, 1000, or whatever fits your needs.