With the Travel SIM card, you will not be able to make phone calls, therefore, please use VoIP applications such as Facetime, Facebook Messenger, Skype, LINE,... (Internet-based calls)
If you would like to have a Japanese phone number, you may consider our Voice+Data SIM / eSIM, which will allow you to make/receive voice calls as well as SMS.
Please see here for more information: https://www.sakuramobile.jp/long-term/voice-data-sim/