PSTN VoIP Application Support System Design using mobile Short Message Service (SMS): Case Study of PSTN VoIP Missed Call Notification to mobile phone by SMS

PSTN (Public Switched Telephone Network) has been generally known for its reliable communication method, although it has so many limitations as compared with mobile telephony, such as lack of mobility, limited features of PSTN terminal or CPE (Customer Premise Equipment), and almost all PSTN services are voice-based only (except Telkom-SMS which was not very succeed). Although PSTN service was gradually replaced by mobile phone, its existence is still needed especially for business users or as secondary option after mobile phone for personal or residential users. This paper gives new ideas to cope PSTN services limitations above by integrating PSTN with mobile Short Message Service (SMS), hence PSTN users can control (i.e. get notifications, register PSTN services, and check billing) its PSTN number easily through their mobile phone (which previously has been joint with its PSTN number) using SMS. In this paper, we limit our project´s scope to a service that can give real-time SMS notifications to PSTN subscriber´s mobile phone if there is a missed call activity to its PSTN number. This idea can be very useful for both PSTN operators and subscribers. For operators, this add-on service can be used as a customer retention program, and for subscribers, this service can make sure that they can still monitor incoming call to their PSTN number even nobody picks up the phone in real time. In this research, Asterisk, an open-source-based Softswitch, is used as call control for PSTN hence we can get the signalling message of all call session activity from there. Our proposed system will capture signalling packet related with missed call activity packet (named 486-Busy Here), parsed the packet by our novel algorithm, and then matched it with Call Detail Record (CDR), the PSTN number with its pair mobile phone number registered, if exist. The output of the algorithm then will be forwarded to Gammu, an open-source-based SMS Gateway, and with specific modification there, it wi- - ll send SMS with certain format to subscriber mobile phone, informing that there was somebody tried to reach its PSTN number.