Asynchronicity is a benefit to me of messaging systems, small businesses (I'm part of one) are more responsive via SMS or Facebook because it's easier to be so. Most calls to us go to answerphone, many times we return a call and get a voicemail service, ... that gets tiresome fast.

With POTS we have to keep contacts separate, with a meeting service contract retention and interaction history - which improve customer service - are built in.