Calling over e-mailing has a number of advantages, you're able to empathize with the person and they're able to hear how comfortable you are with the topic over the phone.

Make sure you have a good headset with a microphone as any background noise is distracting to others during the call. If there is excessive noise on your connection, you will be muted until you need to speak. Make sure you join the IRC channel as links and code examples are usually shared over the chat channel.