Events in mobile's own calendar

Events in mobile's own calendar

Hello,

Is there a way to send events to my customer portal users to their cellphone calendars?

For example, when you have a flight to take, you recieve an email with the date and time and then it automatically appears in the cellphone's own calendar, (not Zoho calendar)

I would like to send events and post them in the user's cellphone calendar, (not Zoho calendar), through my app which runs under the customer portal