# Design and Implementation of a Smart Intercom System through Web Services on Web of Things
## 6 Discussion  
The system is based on a chatbot server in an embedded system that integrates an instant messaging platform to control door locks, cameras, and related devices through web services on the WoT. The system also provides a platform for communication between  
Figure 14: The code corresponds to the “Open Door” message. Figure 15: The code corresponds to the “Alarm” message. Figure 13: The screenshot of the resident’s smartphone. visitors and residents through instant messaging software on smartphones as the primary contact and communication software for residents who do not need to install an additional dedicated app. The chatbot server performs complete control of the door lock, camera, and buzzer through the instant messaging platform. This system lets the resident know the door's status and whether there is a visitor through the system without the resident being at home; so, the visitor cannot know whether the resident is at home or not through the intercom. Moreover, the residents can use the instant messaging software to open the door for themselves and their family members directly, without the need to bring extra keys and sensors. The functions of this system are indeed better than those of the traditional intercoms, and the solutions to improve the functions of the traditional intercoms with VoIP intercoms and mobile intercoms are shown in Table 4.  
The comparative advantages and disadvantages of the existing intercoms are shown in Table 5. The advantages and disadvantages of the existing intercoms can be seen in Table 5, as follows. 1. Only the mobile intercom and this system can be used by residents at any time and place, while the VOIP intercom is possible. Any visitor can use all three systems except the mobile intercom. 2. Only the mobile intercom and this system can provide a wireless way to install use and give the residents sufficient mobility. 3. Only the mobile intercom and this system can provide sufficient flexibility and home security, while the VOIP intercom needs to be set up separately before it can be provided. In summary, this system provides the ability to know if someone is visiting the home when the resident is not at home, and it also provides the ability for the resident to use the system at any time and any place, which also provides flexibility in wireless installation and use and provides sufficient mobility for the residents. Any visitor can also contact the resident through this intercom, while there is no way to confirm whether the resident is at home, which enhances the home's security. While this system is more convenient and secure than traditional intercoms and existing solutions, there are many issues to discuss. \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline
**Type** & **Call/Send** & **Send** & **Send** & **Open** & **Activate** & **Take** \\  & **Voice** & **Text** & **Picture** & **Video** & **Door** & **Alarm** & **Picture** \\ \hline Traditional intercom [1] & Call & - & - & V & V & - & - \\ VoIP intercom [11, 12] & Call & - & - & V & - & - & - \\ Mobile intercom [15] & Send Voice & V & V & V & - & - & - \\ Smart intercom & Send Voice & V & V & V & V & V & V \\ \hline \hline \end{tabular}  
* -: Not supportive. V: Supportive.  
\end{table} 
Table 4: Intercom use functions list. \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline
**Type** & **Use in Any Place** & **By Any** & **Mobility** & **Wireless** & **Flexibility** & **Home** \\  & **by Resident** & **Visitor** & **Mobility** & **Wireless** & **Flexibility** & **Security** \\ \hline Traditional intercom [1] & X & V & X & X & X & X \\ VoIP intercom [11, 12] & \(\Delta\) & V & X & X & \(\Delta\) & \(\Delta\) \\ Mobile intercom [15] & V & X & V & V & V & V \\ Smart intercom & V & V & V & V & V & V \\ \hline \hline \end{tabular}  
* X: Not available. \(\Delta\): Possibly available. V: Available  
\end{table} 
Table 5: Intercom advantages and disadvantages comparison list.