Today companies (especially large companies whose employees make a lot of international business trips) often have very large telephone bills. While international roaming technically works with GSM, the cost of phone calls from one country to another are often much higher than calls within a country. Despite political pressure to reduce the costs of roaming within the European Union, the cost of phone calls from one country to another are often quite expensive. A cost-saving solution is eagerly desired by many firms.
OptiCall Solutions AB has designed an integrated system called the Dial over Data (DoD) solution. In this scheme, a caller sends a data request to the DoD server instead of directly making a call to the party that they wish to speak with. The DoD solution uses an Internet Protocol Private Branch Exchange (IP-PBX) to make two Session Initiation Protocol (SIP) calls, one to the caller and another to the callee, then bridges these two calls. To realize cost savings, the cost of these two calls and the cost of the infrastructure necessary to make the two calls and to bridge them must be lower than the cost of the direct call.
Call Through is a service for making cheap international calls which is provided by many telecommunications companies. Instead of making a direct call to the party the caller wants to speak with, the caller makes a call to the local call-through service access number. The caller dials the actual callee’s number after the call is established. The service provider then makes a call to the callee and bridges the two calls. The caller only needs to pay for a local call and the service subscription fee, rather than the expensive international call fee. This can greatly reduce the costs for user who need to make a lot international calls. Today, many companies use such a call-through service in order to reduce the total cost of their employees’ calls.
Additionally, the Mobile Extension (MEX) is a concept which gives mobile users the ability to use their mobile phone in the same manner as their fixed office phone, for example, by providing services such as setting presence and transferring a call. In addition, the user should experience a consistent interface, for example the calling number displayed for the callee should always be a number that the callee could use to return the call.
In this thesis project, a mobile extension application called ‘OptiCaller’ based on the Symbian OS was developed and evaluated. This application is part of the DoD solution and provides client side functionality. Furthermore, it supports making call-through calls and using the MEX functions. Additionally, it is designed and implemented in a flexible way so that it can work with a variety of different PBX solutions.
A provisioning system called ‘OptiCaller Provisioning System’ was also designed and evaluated. This provisioning system was tailored for the ‘OptiCaller’. It provides administrators a platform to manage the OptiCaller application on the end-users’ mobile phones.
Author: Sun, Tao