Truecaller is a cool tech startup that is focused on building the world's largest crowdsourced phonebook.

Founded in 2009 by Nami Zarringhalam and Alan Mamedi, the Stockholm-based company has over 45 million users. The service lets them block spam calls to their mobile phones and help identify unknown phone numbers.

The app is like an old school white pages and caller ID, but has been totally reborn for the mobile — social era. Users can take advantage of search and discovery features to identify spam calls.

Image: Truecaller

What this means is that you will always be able to tell who is calling your mobile phone — person or business. Spammers or telemarketers or those calls from "Microsoft product support" telling you that you have a virus on your PC are filtered out by other community members.

Last week the company announced that it has secured $18.8M in series B round of funding led by Sequoia Capital, and a partnership with Yelp which complements serious expansion plans for North America.

This partnership enables Truecaller to support building what it claims to be the world’s “largest verified mobile phone community”. The service automatically verifies business numbers that call your mobile phone.

The new service, launched for Android and iOS, integrates with Yelp API data which allows users to identify millions of reviewed businesses globally. It also allows users to block spam callers.

The service gives users access to discovery features such as the ability to search for names, use reverse phone number lookup, share information, and access crowdsourced data.

Image: Truecaller

This has enabled Truecaller to build the world’s largest list of top phone spammers, which has already helped block more than 1 billion unwanted calls in under a year.

When a number that you do not know calls your phone, the service lets you quickly look to see who the caller is, and if it has been marked as spam by other users.

A user can report a caller as spam, and after successive reports within a defined period, that number will be permanently blocked by the community.

Through the free app, which is available on all internet-enabled devices and on the web, you can automatically block all numbers on Truecaller’s top spammers list.

With Yelp integration, users can now identify local, national, and international businesses, and also view their Yelp rating.

Truecaller uses a combination of its search engine to find people and identify numbers, with Yelp’s crowdsourced business ratings to create one location for information.

The company has said that it is committed to expand its list of product features, and the new release incorporates social features to make it easier to update contacts and get in touch with ‘people you may know.’

"2013 was an amazing year for Truecaller and our latest partnership with Yelp expands the value of our service to millions of new users," said Truecaller co-founder and CEO, Alan Mamedi."

More and more users are shunning their landlines in favour of a truly mobile lifestyle. Spam callers make us reluctant to answer our phones.

Crowdsourcing to identify — and block spam calls will be a great benefit to anyone that wants to avoid those nuisance calls that blight our lives.