Operation and Maintenance: Zass Telecom is one of the leading O&M companies in the current Bangladesh market. The company currently looks after the complete DG, AC & Power system for ROBI and Banglalink for Dhaka, Chittagong, Sylhet, Khulna, Faridpur, Kushtia,Rangpur, Rajshahi, Mymensing & Comilla zone. Zass also give different type of refilling solution to operators.