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Published in Gillian M. Davis, Noise Reduction in Speech Applications, 2018
With regard to voice signal quality, one of the primary differences between the PSTN and the VoIP network is that the PSTN provides a dedicated voice channel of consistent bandwidth for each voice call, whereas a VoIP network provides best-effort voice packet delivery consistent with IP network behavior. Another way of looking at this difference is that PSTN voice channels are designed with the voice signal in mind (i.e., they have just the right amount of bandwidth and the right frequency response to minimally support a conversational quality voice signal). IP networks, on the other hand, were never really designed for real-time, dedicated bandwidth applications like voice. This difference affects virtually all aspects of noise and distortion avoidance for VoIP implementations and VoIP/PSTN integration. Another interesting difference is the fact that PSTNs provide call setup and management intelligence in the core of the network (via SS7 signaling and central office processing), whereas VoIP networks have pushed this intelligence to the edge of the network where it resides in VoIP endpoints such as personal computers or IP/ethernet telephones. This can also impact voice quality, because the network core is no longer as tightly controlled or regulated.
Understanding Broadband over Power Lines
Published in Gilbert Held, Understanding Broadband over Power Line, 2016
The key advantage associated with the use of the PSTN is its availability. A subscriber to an online PSTN Internet access plan can obtain a connection from any location that has a PSTN connection. Thus, it becomes possible to access the Internet from the home and office as well as when traveling, with a single Internet account. Concerning the cost of PSTN Internet access accounts, they are the most economical of all Internet access technologies. Although AOL, Microsoft, and other premium Internet access provider costs are in the low $20s per month range, several nationwide vendors now offer unlimited Internet access via the PSTN at monthly rates under $10. Thus, Internet access via the PSTN, although providing the lowest data transfer capability among the competitive methods listed in Table 1.1, is also the lowest cost method.
Network Engineering for Audio Engineers
Published in Steve Church, Skip Pizzi, Audio Over IP, 2012
TDM systems have only audio data within their timeslots. Because there are no signaling or routing instructions in the TDM slots, there needs to be an external mechanism to keep track of where everything is located and to make the needed associations for switching. For the PSTN (public switched telephone network), this is performed by a combination of the logic and storage inside the computers that drive the individual CO switches, and the Signaling System 7 (SS7) protocol that runs between exchanges. The SS7 messaging is carried on data channels independent from those used for speech. In contrast, IP packets “know where they are going” because the destination address is contained within the header of the packet itself. IP routers make all the needed decisions about what to do with the packet based only on the information contained within its header.
Design and implementation of a VoIP PBX integrated Vietnamese virtual assistant: a case study
Published in Journal of Information and Telecommunication, 2023
Hai Son Hoang, Anh Khoa Tran, Thanh Phong Doan, Huu Khoa Tran, Ngoc Minh Duc Dang, Hoang Nam Nguyen
Voice-over-Internet Protocol (VoIP) comprises a set of software and hardware technologies for making voice calls that use a data network instead of a traditional Public Switched Telephone Network (PSTN) system. VoIP is widely used in corporate environments, and the adoption of this technology by businesses is expected to continue growing in the coming years (Packer & Reuschel, 2018). The main reason for the popularity of this model is cost saving. Both large and small companies acknowledge that deploying and managing separate data and voice networks is expensive. In contrast, converged voice and data networks enable unified communications services while reducing costs. Furthermore, the costs associated with traditional phone calls are usually higher than those associated with VoIP calls (Karapantazis & Pavlidou, 2009).