I could see this being a complete disaster. It would basically be the arch nemesis of the chat filter, as you really can't filter voice calls. People would easily abuse this feature. If I were to say anything, stick to Discord, Skype, or TS.
Hey Ryan! I would also love to have voice calls and be able to talk to people I am fighting it would help better coordinate and build relationships through the Wizard101 game, Although then we have to look at the reality of the situation, Wizard101 was built with one of its purposes of keeping children safe from the online world, And adding such a feature would be impossible to monitor making many kids vulnerable, Not to mention how hard it would be to integrate it!
Voice calls would be cool but it would also add a lot more that moderation from KingsIsle that I don't think they really want to do. I believe a better option would be to just make a Discord group with your friends or find a Discord server that has a lot of Wizard101 players in it.
Wouldn't it be awesome if we could add voice calls to Wiz I reckon it would be an awesome idea.
I have a bad feeling people would exploit this and bully younger players, and you can use voice chats like Skype or Discord to talk with your friends anyway.