WhatsApp — the instant messaging app that Facebook acquired for $19 billion last year – hit 700 million monthly active users in January. At the Facebook f8 conference this week, WhatsApp co-founder Brian Acton said that the iOS version of the messaging app will gain the highly anticipated free voice calling feature within the next few weeks, according to VentureBeat. 

WhatsApp spent the last year refining the voice calling feature before it launched on Android last month. WhatsApp’s voice calling feature on Android is limited on an invite-only basis as of right now, but it will likely open up to everyone soon.

Voice calling is different from the voice messages feature that is already available on WhatsApp. Currently, you can send voice messages to your contacts by pressing and holding the microphone icon above the keyboard. The new voice calling feature will let you make phone calls to your contacts, meaning WhatsApp will become more competitive against Skype. WhatsApp revealed it will be adding voice calling to its app over a year ago at Mobile World Congress in Barcelona. WhatsApp’s co-founder Jan Koum also said at the Mobile World Congress event that mobile phones will be sold in Germany with the WhatsApp brand.

A couple months ago, WhatsApp launched a desktop client service called WhatsApp Web. The desktop version of WhatsApp only works for Android, Windows Phone, BlackBerry and Nokia S60 devices right now though. Hopefully, WhatsApp Web will support iOS devices soon.