If two party's want to interact with each other then they could Skype, Face Time (both methods of video call) or just email. All of which are effective but with video calling you get to know the other person better because you can see who you're speaking to whereas on email you cant. You could also text or message via a social networking site such as Facebook or twitter. Messaging via a social networking site is good because if a business client doesn't like a product then you can easily send them a link to a similar one. This also works for video call but instead of sending a link you can show them a product first hand.