It would be really useful to have Calling Over Wifi on Payg @bristolash19911 but as it's relatively a new feature I'm thinking Vodafone will want to make sure any bugs are fully ironed out first On eligible contract types.
And then the next step would maybe to add more handset models.
Vodafone wouldn't generally comment on future plans but there are a couple of official Vodafone pages to watch.
Vodafone Calling Over Wifi. And Vodafone Blog.
Current Phone >
Samsung Galaxy s²³ Ultra 512gb Phantom Black.
