database tables for sending sms for student attandance system

Hai friends
i have been creating tables for sending attendance report and other event information to parents and some event information for staff.
 
table1:student:
It contain details with student_id as primary key
table2:parents:
It contain detail with contact_id as primary key
table3:staff
It contain details with staff_id as primary key
table4:attandance
It contain details with student_id as foreign key
please give me some suggestion about further table creation for sending sms automatically whenever student enter their attandance through finger print device and creating and sending other message through manually.
thank you advance