I don't drive vbus( this is an offending standard situation ) . 2.7 volts came from n900 itself and this is a very weak voltage source .
when an A device make a connection to an B device the A device must drive vbus so N900 can drive vbus somehow and that is a good piece of news. 2.7 V can be easily obtained from 3.3 V inside of isp1707 without charge pump.
An external power source can sense the 2.7v on vbus and drive with 5V hubs, sticks, et c.

i got int 941 when doing **** things on datalines