WhatsApp is now available in beta, and it will work in your new iPhone if you have it jailbroken.
Installing WhatsApp beta has some privileges such as enabling voice calling in WhatsApp. AppSync should be installed prior to get this to work in WhatsApp beta.
You can do so by adding this source in Cydia: http://cydia.angelxwind.net
- Download and install the WhatsApp beta you can do so by clicking here make sure you are doing this from your iPhone.
- Get the following repo added to your Cydia sources: http://apt.imokhles.com
- Download the WhatsApp Call Enabler package, afterwards in Settings you can enable it.
- Login to WhatsApp and test it by messaging a friend with activated calling this way you can be activated.
- Once you get your friend to return your call you should then have the calling feature become activated.
All the steps required are listed in the tutorial video below: