Ashish,
There are a couple of ways to achieve this.
Firstly, you can use the built-in Time Zone Blocking functionality. You don't say where you are located and the options are slightly different depending on whether you are in North America or not. (End then they are slightly different between the US and Canada!) Assuming you are outside the US, you add a TimeZone column to the contact list and then create a Zone Set to specify acceptable calling times for each time zone. (For completeness, if you are in North America, you can have it work out the Time Zone automatically, based on the phone number. Additionally, if you are in the US you can use the ZIP code as well.)
If your requirements are little more nuanced (where each contact has a unique acceptable calling window) then you could use a pair of pre-call rules to see if the time is before the start, or after the end, of the window and to not dial that contact.
HTH
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Paul Simpson
Views expressed are my own and do not necessarily reflect those of my employer.
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