Call Steward notifies you via email or SMS.  

For the user this is a personal choice so we have a user control for that.

Get logged into the web portal or desktop site.
This control is not available in the mobile view as of yet.

Click on My Profile and then Settings.

then in the third box on the right, you select email or SMS.  Also, please note the STOP tool, should you go on vacation.

Navigate away and then come back to make sure the switch is set.

And your done!