Instant Messaging (IM) is becoming increasingly popular in social as well as workplace environments. In fact, many employees use the same IM client to communicate with both colleagues and social contacts. Thus, there are valid concerns about the impact of IM on employee productivity. One of the major advantages of IM over other workplace communication tools such as e-mail and the telephone is the implementation of presence information. In particular, presence awareness is used to determine the avail- ability and willingness of a contact to engage in communication. A current problem with IM is the one-for-all approach to presence: all contacts receive the same set of presence information. However, presence is rooted in social psychology where it is known that the awareness of another person changes the behavior of oneself. Therefore the identity of a contact affects the availability and willingness directed towards that contact. In order for presence information to be provided to contacts, it must be represented in some type of data format. The Internet Engineering Task Force (IETF) has done much work in standardizing IM and presence systems. In particular their data format for presence describes a rich set of presence information including, but not limited to, location, activity, awareness, and mood information. Such information may be sensitive and access to it needs to be controlled to ensure privacy. As with access control policies, managing the information as the number of contacts increases becomes cumbersome and complex. This dissertation draws on the theoretical foundations of presence, current standards in the domain of IM, and lessons from access control to present an enhanced presence handling model for IM. The model is developed in stages, with each stage providing a specific improvement. The first stage of the model is grounded on the current work of the IETF. As such it distributes presence on a per-watcher basis. In the second stage of the model watchers fulfill a specific role and based on this role they receive only the entrusted presence information. In practice, it implies that a "friend" may get more (or less) information than a "colleague". The third stage of the model introduces the concept of availability profiles by drawing on social awareness principles. Availability profiles add the ability to transform presence and change the presentity's behavior to incoming messages according to the provided presence information. Finally the dissertation reports on the development of the RoBIM (Role- Based Instant Messenger) prototype. RoBIM is a standards-based IM system that conforms to the IETF SIMPLE protocol and provides various standard IM features. Here, RoBIM serves as a proof-of-concept for the proposed model. This study contributed to the domain of IM and presence by addressing some of the current presence handling issues. Most importantly, the proposed model takes into account the interpersonal effects of individualizing presence information for different contacts. Thus, the model challenges conventional thought and implementation of presence in IM.

The following thesis aims to describe the transformation of telco operators' business strategy evoked by the growing popularity and usage of Internet services like WhatsApp, Skype and Netflix, also known as over-the-top services. The thesis provides comprehensive overview of transformations in the telecom industry that have been taking place globally, explaining the drivers that led to inception of free or cheaper Internet-based services, their business models. It then narrows down to the thorough analysis of the Czech market, capturing the implications that over-the-top services have on business strategy of the major Czech telco players. The analysis is strongly supported by industry reports, statistics and quantitative research. The primary research adds in telco customers' perspectives, usage and value perception of over-the-top services, as well as their satisfaction with respective telco services and their pricing. Derived findings identify major developments and trends in the Czech telco market; they also suggest compelling observations for related businesses.

This master thesis is focused on designing the client and the server part of an application for text and multimedia communication between its users. The design takes into account reusing of the components and making them easily embeddable into another application. The project consists of a detailed analysis of communication protocols used for this type of applications, a description of possibilities of the iOS platform and development on this platform. Finally, the implementation and its possible extensions are described.

Magister Commercii (Information Management) - MCom(IM) / South Africa has one of the largest HIV and AIDS burdens in the world, with an estimated7.52 million people living with HIV in 2018. The antiretroviral therapy (ART) programme is the biggest and most costly programme in the country, with 3.7 million people enrolled as of 2017. The success of antiretroviral therapy is dependent on adherence to medication and long-term retention in care. It has been reported that support groups can improve the treatment adherence of patients and their retention in care. However, enrolment in adherence support groups is voluntary, and the abovementioned success thereof is dependent on the commitment of the patient to active participation in the group. It is estimated that about 80% of adults and young people own at least one mobile phone, which makes this technology suitable to improve communication and enhance interaction amongst support group members.

Esta investigación tiene como objetivo principal identificar la relación de los mensajes de texto en la comunicación de acciones de endomarketing y su influencia en el compromiso organizacional del cliente interno. Para ello, fue hecha una revisión de la conceptualización en torno al compromiso organizacional, a partir del modelo de Allen y Meyer, y su importancia para la mejora de la empresa. Seguidamente fue estudiado el tema de endomarketing o marketing interno en relación con la comunicación de acciones internas, los servicios de mensajería y su relación con el compromiso. La investigación, dirigida a los colaboradores de la Clínica Ricardo Palma durante la actividad de Olimpiadas 2017 apunta a comprobar una asociación negativa entre el compromiso y los servicios de mensajería, pese a ser un canal bastante cercano a un usuario. Haciendo uso de un estudio de caso con enfoque cuantitativo concluyente, se evaluó un total de 142 colaboradores, a través de encuestas. En ambos casos se evaluó por medio del cuestionario de compromiso de Allen y Meyer realizado por María Bohnenberger (2005) sobre la asociación de endomarketing con compromiso; además se hizo uso de la percepción de los canales de comunicación de Herrera (2011), todo bajo escala Likert. La parte final de la estructura corresponde a la descripción del caso, análisis y resultados, donde se buscará demostrar el grado de relación de los servicios de mensajería (SMS) como medio idóneo y su incidencia en el incremento del compromiso. / The main objective of this research is to identify the relationship of text messages in the communication of endomarketing actions and their influence on the organizational commitment of the internal customer. To do this, a review of the conceptualization around organizational commitment was made, based on the model of Allen and Meyes, and its importance for the improvement of the company. Next, the issue of endomarketing or internal marketing was studied in relation to the communication of internal actions, messaging services and their relationship with commitment. The study, aimed at employees of the Ricardo Palma Clinic during the 2017 Olympics, aims to prove a negative association between commitment and messaging services, despite being a channel that is quite close to a user. Using a case study with a conclusive quantitative approach, a total of 142 collaborators were evaluated through surveys. In both cases the commitment questionnaire by Allen and Meyer was evaluated by María Bohnenberger (2005) on the association of endomarketing with commitment; in addition, Herrera’s (2011) communication channels perception was use, under Likert scale. The final part of the research consist of a description of the case, analysis and results, where the aim is to demonstrate the degree of relationship between messaging services (SMS) as an ideal resource and its impact on increasing commitment. / Tesis

The Signal protocol provides end-to-end encryption for billions of users in popular instant messaging applications like WhatsApp, Facebook Messenger, and Google Allo. The protocol relies on an app-specific central server to distribute public keys and relay encrypted messages between the users. Signal prevents passive attacks. However, it is vulnerable to some active attacks due to its reliance on a trusted key server. A malicious key server can distribute fake keys to users to perform man-in-the-middle or impersonation attacks. Signal applications support an authentication ceremony to detect these active attacks. However, this places an undue burden on the users to manually verify each other's public key. Recent studies reveal that the authentication ceremony is time-consuming and confusing, and almost nobody adopts it. Our goal is to explore various approaches for automatically detecting or preventing fake key attacks. We modified a local copy of the Signal server to demonstrate that active attacks are feasible. We then designed three defenses that automatically detect or prevent the attacks. We completed a threat analysis of the defenses and implemented some proof-of-concept prototypes for two of them. We analyze their strengths and weaknesses and outline avenues for future work.

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The lack of physical communication cues, such as facial expressions, in text-only communication has prompted the creation of emoticons to represent feelings. Moreover, the emoticon has become a new “cultural” language adopted by a community of users who find emoticons useful for expressing an emotional state during their online communication. Using emoticons in computer-mediated communication (CMC), which includes any means of communication on the Internet, especially instant messaging (IM) programs, helps users convey and enhance the underlying emotional aspects of their communication facilitating user communication by providing non-verbal cues and clues to clarify a message. Although many researchers have studied the differences in the use of emoticons between males and females and different age groups and some even report cross-cultural differences and similarities between CMC and face-to-face (FTF) communication such research is not sufficient to understand the effective use of emoticons. The current research explores three categories of emoticons - textual, pictorial, and animated emoticons – to ask the broad question: Do North Americans and South Koreans use emoticons differently? The research examines the cross-cultural differences involved in using emoticons, focusing on the visual aspect of online communication that provides emotional cues to understand the differences in their use. Textual emoticons and pictorial emoticons of MSN messenger are used in this study's questionnaires. The results indicate the cross-cultural differences of emoticon use and recognition between North Americans and South Koreans.

Text messaging is a significant social phenomenon that merits investigation. Communications theories are well suited to this type of research because text messaging serves as both mediated communication and interpersonal communication. This kind of research can also contribute to a deeper understanding of communication differences between genders. The purpose of this study was to ascertain whether there are gender differences in the use of text messaging and, if so, what the differences are. Participants for the study were recruited via convenience sampling. The sample consisted of 27 participants ages 18--35; 14 were female and 13 were male. Data were collected from the participants via the focus group approach. Two of the groups consisted of females, and two of the groups consisted of males. Transcripts of the focus group sessions were analyzed using the constant comparative approach. This approach involves continually sorting through the data, comparing categories, and analyzing the resulting information. Areas of difference between the genders include selecting recipients, gathering information, seeking entertainment (trolling), ending relationships, arguing, seeking privacy and exclusion, using text shorthand and slang, remaining alert, and using text messaging for dating. These findings provide new insight in the areas of text messaging and gender studies.