Possible reasons you might not be getting your notifications from Infinite Campus Messenger:
Information is not up-to-date in the school information system
You've changed your phone number/email but not updated your account with Campus Messenger
Full mailboxes or answering machines.
Line echo - encountered most often on digital phone services.
Poor cell phone signals.
Bad connections on land lines.
Answering machines or voice mails that drop calls.
Auto-attendant messages that require user interaction to leave messages.
Non-standard answering machine beeps.
Excessive amounts of background noise.
Local phone company switch congestion.