Interesting, but this doesn't address the fundamental problem. The main reason that companies make you wait on the line is to differentiate the customers who care a lot about their problem from those who don't. By making the cost of waiting, for the customer, practically negligible, you are sidestepping this protection mechanism; your success would flood companies with less important support calls, thus giving them a powerful incentive to shut you out. At first, they'll just instruct their customer service representatives to immediately hang up on anything that sounds like your service. Next they'll ask the legal department for ammo, and do their best to implement technical counter-measures.

It's an interesting idea, but it's IMHO doomed long term, unless you find a way to take the companies' interest into account as well. For instance, in order to maintain the same system of customer disincentives you should probably charge per each minute your service is used.