domain name resolution

i have a vsat link with an isp in the U.S,my location is Lagos,Nigeria.i want to know how i can have internet packets resolve at my local dns and how that might improve voice over the link.i intend to share my link with client locaton in Lagos too. all i have is the IPSAT provided by the isp, i do not have a router or switch, would i need any of these equipments?