Eventually, when smaller upstarts come along, the monopoly points at them and says, "Hey, these guys aren't playing by the rules" and then the government makes these upstarts comply with expensive regulations.
For instance, VOIP and 911. When you could get VOIP for nothing (or next to it) the big telecoms pointed to these new providers and said "We have to support 911, why don't they?".
In this case, the government jumped in to help the telecoms keep a foot hold on their monopoly. See: http://www.sandiegobusinesslawfirm.com/net_telephone_service...
This pattern repeats itself in almost all legislation attempting to regulate monopolies. In the end, it only serves to stifle competition and remove consumer choice from the market.