While I agree that both are important... Voice chat is a great way to learn intonation, pronounciation and idiocynracies that are so unique to English, but because we have so many odd grammar rules and spelling difference, you absolutely need to chat by typing/writing, too.

if I tell you that chating is more important than typing for you to learn english,will you stop type.obviously ,you won't ..learing one language involves many aspects.you have to learn listening\speaking\writing and reading,and of course including typing,since communicating online become an important part of our life.To learn as much as you can to use the lauguage as a native speaker...

by listening, you could learn faster. but, you cannot abandon writing. because both of them are important. but, i prefer voice chat to chatting

A live teacher is even better.

Both are a good way to learn and can help you to practice.