[nmhusa]

From what I understand the USB voltage has two modes.... a lower one that is standard on all hubs etc and a higher power draw that a device (like the TP2) needs. I have on more than one occasion now, found the TP2 fully drained despite being plugged into a USB charger hooked to a wall adapter. The screen usually states low power draw as a warning. USB cables plugged into a PC, Notebook or car adapter work fine.

If you are using a dedicated TP2 wall adapter, usb cable plugged into a PC or a car adapter, you should be able to talk and charge at the same time.