Telephone systems commonly transmit narrowband (NB) speech with an audio bandwidth limited to the traditional telephone band of 300-3400 Hz. To improve the quality and intelligibility of speech degraded by narrow bandwidth, researchers have tried to standardize the telephonic networks by introducing wideband (50-7000 Hz) speech codecs. Wideband (WB) speech transmission requires the transmission...

We propose an on-demand VPN service for home NGN users. This service enables users to connect home LANs without setting up complex network configurations. Users can specify a destination LAN by dialing a telephone number on an ordinary telephone terminal. We developed prototype residential gateways to provide the on-demand VPN service. The gateways find the IP addresses of peer gateways and sui...

This paper proposes a new mathematical model to describe the distribution of the occurrence of errors in data transmission on telephone lines. We suggest: a) that the statistics of telephone errors can be described in terms of an error probability depending solely on the time elapsed since the last occurrence of an error; b) that the distribution of inter-error intervals can be well approximate...

Although current national response plans assume that most influenza-infected patients would stay home during a pandemic, surveillance systems might be overwhelmed and unable to monitor their health status. We explored the feasibility of using a nationwide telephone survey to monitor at-home patients. Of randomly selected adults surveyed during low influenza activity months (April-October 2006, ...

It is highly desirable to collect speech data from the telephone network via a digital interface. This avoids an additional A/D conversion normally required by analog telephone data collection hardware. A popular solution to this problem is the use of a T1 line which offers 24 digital phone lines. The leading T1 interface for Sun workstations is a system developed by Linkon Corporation. Using t...

Codecs used in telephone networks in the United States have a -law companding characteristic solely designed for the purpose of transmitting voice signals [1, 2]. These -law codecs are not well suited for the latest generation of high-speed digital voiceband modems requiring PCM data transmission at the quantization levels of the codec [3, 4, 5, 6, 7, 8, 9]. In this paper, we have shown that us...

In this paper LMDS, satellite systems, stratospheric platforms, DECT, PACS and PHS have been chosen as possible WLL technologies in rural areas of Pakistan. The low population density and great distances in Pakistan’s rural areas make the installation of a fixed line telephone network prohibitively expensive. The result is that after 55 years there are still a large number of under-provisioned ...