iSkoot, a Cambridge, Mass. company that lets people make Internet calls on their mobile phones, has raised $7 million in a second round of funding from Charles River Ventures, Khosla Ventures, ZG Ventures and Jesselson Capital.

ISkoot raised $6.8M in Novemer (see our earlier coverage).

iSkoot software is pre-loaded onto Nokia and Sony Ericsson handsets used by The 3 Group to offer the mobile Skype service.