If window phone users update their Truecaller app by October 30, then they get free 30 days premium access.
Features:
Truecaller for Windows Phone 8.1: Now with automatic incoming Caller ID! The easiest way to search contact numbers, block spam and identify incoming calls on your mobile phone so that you always have access to the right information, people and businesses you need.
• Search for any number whether it’s local or across the World
• Know who’s calling with incoming Caller ID even if you don’t have their number in your address book
• Block calls from spam callers and telemarketers
• Save numbers directly into phonebook
• Simple, organized, and easy to use
• + more features to make contact management run smoothly