Your phone is doing the Right Thing™. Feel free to read up on the USB 2 specification (warning: link leads to a 28 MB .zip). In short,

• USB devices can be low or high power.
• The maximum current is limited to 100 mA in low and 500 mA in high power.
• Any device must start as low power on plugging in to the host and negotiate switching to high power only after a successful negotiation.
• Shortened data pins override the need for power negotiation as well as the 500 mA limit.

Your phone follows these rules. On plugging in, it tries to detect shortened data pins. If not detected, it has to assume that this is a host USB port and not a charger, so it tries to negotiate the high power. This obviously fails so your phone remains in low power mode, where only the USB controller chip is powered (maybe not even that, since the phone has its own power source).