Offloading of SMS messages for cellular phones by e-mail reception notification via the Internet

In the Great East Japan Earthquake people could not use the telephone service of a cellular phone because the huge voice traffic pour into mobile network and cellular carriers took the measure of the originator regulation. Although the Internet was useful in the less affected areas, the delivery of the cellular phone e-mails delayed in the less affected regions like Tokyo. This paper derives the delivery delay of cellular phone e-mails from the SMS congestion affected by the originator regulation since the system of cellular phone e-mail uses SMS for the reception notification. We need the solution against SMS congestion or the method of the immediacy notification in a disaster to improve the delivery delay of cellular phone e-mails. This paper proposes a method of the reception notification via the Internet to the smartphones using Wi-Fi, These smartphones can receive a cellular phone e-mail immediately and this offloading of SMS messages contributes to reduce the load of SMS. Based on the real data monitored at the Great East Japan Earthquake, which announced 90% of e-mails were delivered within 80 minutes, we analytically investigate the effect of delivery performance improvement and show this required time is improved to about 30 minutes assuming all the mobile terminals are smartphones half of which are connected to Wi-Fi.