...[I]nvestor members of CRN [Conflict Risk Network] sent letters to telecommunications and oil and gas companies operating in Sudan, "calling on them…to ensure they do not infringe on human rights" as the country prepares for the January referendum...[B. Freeman, Calvert Asset Management (member of CRN):] "The potential for violence, instability and human rights violations around Sudan's referendum process challenges companies…not to become complicit in such violations."...CRN describes the two-fold engagement undertaken by the investor group...Stating that "mobile technology is vital for the exchange of information in Sudan," the investors are engaging with Zain Group and MTN Group...The second engagement targets 18 companies in the oil and gas sector, including China National Petroleum Co…to ensure that the “companies prevent association with human rights abuses akin to those committed during Sudan’s previous civil wars by security forces linked to oil consortia.”…[Also re: Boston Common Asset Mgmt., Domini Social Investments, PetroChina, Sudatel]