Abstract: An analysis method provides a bandwidth calculation for employing voice communications over fast packet (FP) networks such as frame relay or ATM. Many companies currently have internal phone systems such as private branch exchange (PBX), which provide for the transmission of voice communication within an enterprise, but also a connection to the public switch telephone network (PSTN). In addition, PBX systems may be interconnected via a system of inter-PBX tie trunks, generally used for internal PBX-PBX communication. If a PBX system employs a private data network utilizing FP technology such as frame relay, it is now possible to route this inter-PBX voice traffic over the data network. In situations where the data network is a FP network such as frame relay or ATM, an analysis is performed to determine whether there is sufficient bandwidth to handle the voice traffic.