The Ascom Unite system provides a series of modules connected to each other containing applications used to deliver services over an IP network. Its main purpose is to provide a reliable and a flexible architecture independent from the adopted radio carrier technology: in this way it is possible to integrate wireless phones, pagers, GSM phones in the same system and provide them common functionalities.
All the available modules are tightly integrated and they exchange data us-ing the proprietaryUnite protocol built on the top of the TCP/IP stack. Each module runs on an hardware platform called ELISE (Fig. 4) and contains: a host router which handles all the communication to, from and internally in the module, a UNS (Unite Name Server) used to translate the call IDs into inter-nal addresses, a Web Server that provides a web-based user interface for the module’s configuration, a Linux based operating system and a Host Attendant which handles the basic configuration and supervision of the installed software [26]. Each module contains specific software, marked with X and Y in Fig. 4, required to carry out specific functionalities.
All toghether, the modules constituting the Ascom Unite System, provide the following services [26]:
• Messaging: enables external applications to send text messages to a spe-cific destination (e.g a wireless phone or a GSM phone).
• Interactive messaging: enables external applications to send particular messages containing different response options.
Figure 4: ELISE hardware, [TD 92243GB] pg. 7
• Personal alarm handling: enables the reception of alarm events from porta-bles.
• User data: enables external applications to receive user data from porta-bles.
• Remote management: it allows the management of all the modules of the Ascom system over an IP network.
• ESS centralized services: number planning, message routing, group han-dling, system supervision, fault and activity logging.
In the following will be given a brief description of the modules used (or replaced) by the context-aware application, the wireless phones, the IP-DECT station and the location sensors.
3.2.1 Enhanced System Services - ESS
The ESS module represents the central unit of the Ascom Unite System: it manages all the calls between phones. This componentwill be replaced by the context-aware application with the PBX trixbox in order to override the stan-dard call management. It is worth, however, to take a look at the functionalities it provides [26]:
• Number Planning: by using the web-based interface provided it is possible to manage the centralized number planning and handle phones and pagers regardless the carrier system on which they are connected to.
• System Supervision: enables the supervision and control of all the modules installed in the system.
• Group Handling: portables from different carrier systems can be grouped together within the same category. This functionality is useful to apply the same policy/rule for a whole group of phones.
• Fault Handling: faults from other Unite modules can be collected and stored inside a dedicated log file.
• Activity Logging: collects inside a log file events, alarm data, messages and location data sent by the phones.
3.2.2 Integrated Message Server - IMS
This is a middleware between the IP-DECT base stations and the other modules of the Ascom Unite system. It handles all the data coming/directed to the phones and supports the following services [26]:
• Message distribution: it allows to specify where information coming from the phones has to be distributed. For example,location or user data can be distributed to the Open Java Server.
• Central Phonebook: a central phonebook accessible from all the phones can be stored inside the module.
• IMS Messaging Tool: is a web-based tool for sending messages to the handsets.
3.2.3 Open Java Server - OJS-GSM
Open Java Server is a programming server directly interfaced with the IMS.
This module allows to mount a Java program on it implementing customized features not covered by the standard Ascom Unite System. The different kind
Figure 5: OJS interactions with the IMS Messaging System, [TD 92230GB] pg.
1
of data (shown in Fig. 5) that this server can receive/send from/to the IMS are:
• Standard Messages
• Interactive Messages (IM) with multiple response options.
• User Data (e.g sent by the phones when one of the three soft keys is pressed)
• Location
• Alarms
In order to communicate with the IMS messaging system, each program mounted on this server must use the OAJUtil Java package provided by the module. OA-JUtil is an API containing specific libraries that can be used to manage all the information listed above.
3.2.4 IP-DECT Base Station
The IP-DECT Base Station, shown in Fig. 6, works as a bridge for data ex-changed between the Ascom wireless phones and the Ascom Unite wired net-work. Its main characteristics are the following [26]:
• DECT GAP/CAP radio interface
• Supports H.323 or SIP protocol over IP
• On-air synchronization
• Web interface for configuration and software upgrade
• Roaming and handover
• handling of 8 simultaneous calls
Figure 6: Ascom IP-DECT Base station, [TD 92370GB] pg. 1
Therefore, all the communications between handsets and the Base station are carried out over the DECT protocol.
3.2.5 Handsets
The two models of phones provided by the Ascom equipment at our disposal are the 9d24 MkII and d62, shown in Fig. 7. The d62 differs primarily for its intuitive and coloured display not available on the 9d24 MkII. Both provide a
Figure 7: Ascom’s wireless phones: the 9d24 MkII on the left and the d62 on the right, [92380GB] pg. 1
number of advanced functionalities such as built in alarms, SIM card for identity and personal settings, advanced messaging functions, up to 10 profile mode with customizable settings and3 programmable soft keys for each profile which can be used to push user data to the Ascom Unite system, highlighted with red squares in Fig. 7.
3.2.6 Location devices
The Ascom equipment is also provided with location devices used to track hand-set’s positions. Every time the position of a phone changes and fall into an area covered by a specific location device, the ID code of the sensor is sent by the phone to the base station.
3.2.7 Data and call flow within the Ascom system
Before continuing with the description of the other framework’s components, in order to make clear to the reader which components of the Ascom Unite System are involved in a typical communication scenario during the sending of data or the execution of a call between phones without considering the context-aware application, a brief explanation will be now given.
• The data flow is shown in Fig. 8. When a new message containing location or user data is sent from a device, it is first received by the IP-DECT base station. Then, the base station routes data towards the Integrated Message Server (IMS) which finally distributes the information to the
Figure 8: Data flow
Open Java Server GSM. In order to route the data in this way, the Ascom system has been specifically configured. Its configuration is given in the Appendix B.
• The flow followed by calls is slightly different from the previous one and it is illustrated in Fig. 9. All the incoming calls are routed by the IP-DECT
Figure 9: Call flow
base station to the Enhanced System Services component. ESS checks if there are routing policies to be applied and then, according to the out-come, deliver the call to the right recipient. The call flow just described will be completely modified by the context-aware application in order to properly manage the control of the phone calls.