Is there any way to have Whatsapp call feature enabled on O2 iPhone 5S on iOS 8.3? I have googled and found few like these: How To Enable WhatsApp Voice Calling On iPhone Redmond Pie Enable WhatsApp Call Feature on iPhone - Cydia Pie But they require jailbroken iPhone. Help will be appriciated.
In the WhatsApp app, open a chat. At the top right, you'll find a phone icon. Tap it to make a phone call. You don't need a jailbroken iPhone to do this. Hope that helps.