Starting today, WhatsApp, the most popular messaging app in India, will let you make video calls; just like FaceTime and Skype, the calls will be free, though if you aren't on Wi-Fi you may have of course to pay for cellular data usage, depending on your plan. The video calling feature will be available to Android, iPhone, and Windows Phone users via an app update later on Tuesday.

WhatsApp, which is owned by Facebook, also announced that it has over 160 monthly million active users in India, making the country its biggest market. WhatsApp says the new video calling service is optimised to work in regions like India, where users often struggle with poor Internet connectivity. "[...] we want to make these features available to everyone, not just those who can afford the most expensive new phones or live in countries with the best cellular networks," WhatsApp added.

"We’re obsessed with making sure that voice and video work well even on low-end phones," Koum said.

Just like WhatsApp messages and voice calls, video calls will be fully encrypted end-to-end, making it technically impossible for the company or government authorities to read messages or listen to calls. The new video calling service will thus provide another means for people to communicate without fear of eavesdropping though WhatsApp does retain other data such as an individual's list of contacts.

(Also see: Eight WhatsApp Features That Would Make 160 Million Indians Very Happy)

The video calling feature, which has been available in the beta app for a while, works just like WhatsApp voice calls - when you press the little phone button on a person's profile, WhatsApp will ask you if you want to make a voice call or a video call. WhatsApp video calling will be available to all users running the latest version of the app, and if you are running a previous version, you are advised to update to the latest one. If you don't see the WhatsApp video calling feature, you can get access by following these steps.

With the addition of video calling, WhatsApp will compete with the likes of Apple's FaceTime, Microsoft-owned Skype, and Google's newly launched Duo - among others - for a share of the video calling market. WhatsApp started as a text messaging service, and as its popularity grew, it has added features like voice calling - introduced in March last year - and now it has added video calling.

Written with inputs from Reuters