But for the most part I think phone support is a less efficient way to work and actually waste a lot of time both for the customer (waiting in line) and support side. It's expensive for the company but because it's expensive and cumbersome it works as a form of escalation. And given that they are wasting time & money keeping someone on phone might mean they provide some form of support. At least thats what I think.
So it really isn't the best way to support for the most part. But depending on the issue after its triaged, tracked through a issue tracker sometimes a proper phone/conference call might actually be helpful.