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<p>Telia Telesvar is an automatic anwering machine that is provided in your stationary telephone at home. The drawback of this is that you cannot see if anyone has called you. </p><p>This report describes how a terminal for Telias Telesvar could be designed. Telesvar terminal will show in a display if anyone called you and show the incoming number. It will also play the spoken message in a built in speaker. </p><p>The design is based on some key components, LCD (Liquid Crystal Display) and DTMF (Dual Tone Multiple Frequency) and PIC16F877 microcontroller. These components are also described in the report.</p>

Telia Telesvar is an automatic anwering machine that is provided in your stationary telephone at home. The drawback of this is that you cannot see if anyone has called you. This report describes how a terminal for Telias Telesvar could be designed. Telesvar terminal will show in a display if anyone called you and show the incoming number. It will also play the spoken message in a built in speaker. The design is based on some key components, LCD (Liquid Crystal Display) and DTMF (Dual Tone Multiple Frequency) and PIC16F877 microcontroller. These components are also described in the report.

Made available in DSpace on 2014-06-12T17:39:56Z (GMT). No. of bitstreams: 2 arquivo6989_1.pdf: 3172378 bytes, checksum: a9059211da85af72e928d6791b65a998 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2004 / A sinalização DTMF (Dual-Tone Multifrequency) tem diversas aplicações importantes, sendo usada em muitos sistemas de Telecomunicações, tais como telefonia a teclado, correio de voz, comércio eletrônico e sistemas bancários interativos. Com a demanda crescente por taxas de transmissão cada vez mais elevadas nesse contexto, a velocidade de decodificação dos sinais DTMF torna-se um parâmetro importante no projeto desses sistemas. Uma vez que a decodificação é realizada via multiplexação temporal em um processador digital de sinais, um menor tempo de decodificação implica capacidade de processar simultaneamente um maior número de canais. Esta dissertação propõe um novo método, baseado na Transformada Aritmética de Fourier, para a decodificação dos sinais DTMF. O método proposto é mais eficiente, em termos de complexidade computacional, do que as técnicas usualmente utilizadas nesse cenário. São enfatizadas as vantagens computacionais que esta nova técnica oferece sobre outros algoritmos que calculam a Transformada Discreta de Fourier. Resultados de simulações são apresentados e algumas implementações são sugeridas. Uma breve análise do desempenho do método proposto, na presença de quantizadores, é feita

The success of the Internet has brought significant changes to the telecommunication industry. One of the remarkable outcomes of this evolution is Voice over IP (VoIP), which enables realtime voice communications over packet switched networks for a lower cost than traditional public switched telephone networks (PSTN). Nevertheless, security and privacy vulnerabilities pose a significant challenge to hindering VoIP from being widely deployed. The main object of this thesis is to define and elaborate unexplored security and privacy risks on standardized VoIP protocols and their implementations as well as to develop suitable countermeasures. Three research questions are addressed to achieve this objective: Question 1:  What are potential unexplored threats in a SIP VoIP network with regard to availability, confidentiality and privacy by means of unwanted traffic and information disclosure? Question 2:  How far are existing security and privacy mechanisms sufficient to counteract these threats and what are their shortcomings? Question 3:  How can new countermeasures be designed for minimizing or preventing the consequences caused by these threats efficiently in practice? Part I of the thesis concentrates on the threats caused by "unwanted traffic", which includes Denial of Service (DoS) attacks and voice spam. They generate unwanted traffic to consume the resources and annoy users. Part II of this thesis explores unauthorized information disclosure in VoIP traffic. Confidential user data such as calling records, identity information, PIN code and data revealing a user's social networks might be disclosed or partially disclosed from VoIP traffic. We studied both threats and countermeasures by conducting experiments or using theoretical assessment. Part II also presents a survey research related to threats and countermeasures for anonymous VoIP communication.

Technology nowadays is evolving at rates that surpass anything imagination could perceive and it certainly affects every public or private enterprise. Well, according to this topic, I’m suggesting the improvement of the communications network of the Regional Government of Lima based on an integrated data and voice platform which includes a Cisco Centralized IP Telephony solution, called Cisco Unified Communications Manager 7.0, that works as a main element in order to achieve meaningful and complete management of internal and external telephone calls within MPLS Networks. Regional Government of Lima has been chosen because of its importance related to the economic activities of the population and the support that could be brought by an institution which could make success and generate productivity about rapid administrative processes . The thesis is divided into distinct chapters that make up the context of the investigation which involves network planning and design as an iterative process, encompassing topological design, network realization, IT asset sourcing and operations planning. For this purpose, information about the old and non sophisticated network status was raised. Costs and more details such as hardware and software features and more ways to make this network work so much better, with all the resources at its disposal, will be found on this whole solution