They are charging only 9.6 cents per month per number. If they raise this to 9.6 dollars per month per number, any compay with <10 numbers will not see any difference in it's anual budget.
Does anyone even pay for phone sex anymore? I'd thought that business model went out with dial up ISP's and people screaming in a trading pit on the stock exchange.
The solution to this is the same as the solution to spam... kill all who respond. They are too stupid to live in this society.