Telco TelMex blocking VoIP and "always on" internet applications

So it looks like VoIP users in Mexico are getting a bit of the same treatment we got here in the States when a local telephone company decided to block ports used for voice over IP calling. Many callers there are reporting no service or very poor call quality. Since provider Telmex owns 95% of the telecommunications infrastructure in Mexico, this doesn't bode very well at all for the VoIP market there. The response from Telmex at this point seems to be that they reserve the right to provide a different level of QOS (quality of service) for specifically internet applications that are "always on," which appears to be attacking customers using P2P systems as well as VoIP calling — and literally, any other application in which "applications establish constant communication" and "the equipment is permanently emitting information." Truly, there aren't terribly many internet applications that aren't always on anymore, and Telmex's attempt to parcel up each type of transaction and implement control mechanisms to charge higher rates or offer different levels of service depending on what's going on at the application layer seems way too complex to be practically viable. It's also not a very promising model for a large telco to be adopting and, apparently, getting away with.