As part of its new “Alter Ego” ad campaign, T-Mobile posted the above TV commercial comparing the speed of the iPhone 4S on AT&T to devices on its 4G network. The carrier recently did a similar comparison when launching its Test Drive tool for comparing its 4G devices with the iPhone on other networks. In related news, yesterday we reported T-Mobile was preparing to rollout an iPhone-compatible 4G HSPA+ 19000 MHz network to various markets by the end of the year.

Although many thought the comparison of the 3G iPhone on AT&T to 4G Android devices on T-Mobile was unfair, Apple is rumored to launch a new LTE iPhone following the introduction of the new 4G iPad last March. Recent reports indicated Qualcomm was having trouble meeting demand for LTE chips likely to land in the next-gen iPhone, indicating T-Mobile will likely have to take a new approach to its ads come October.