If you go to Admin > Comms> Logs > SMS & App only you are able to check for all sent SMS messages.
Identify the SMS by the date and time sent. At the end of the row you can view how many of those SMS sent failed. Click on the Total Sent figure to view the recipients and the SMS status.
A common reason a SMS fails is due to the recipient being 'out of range' (if they have poor mobile reception at home or their workplace; it will attempt to send and then stop after a period of time). SMS will also fail if the carrier is international or the recipient is overseas. If SMS are unreliable for this contact due to mobile reception, you may wish to check if an email or App message is more appropriate for them.
Check the student's profile associated with this contact, and check that they have Contact by SMS set to Yes. Also check that the mobile telephone number is assigned to Mobile (M) and not Home (H); Home is only for landline numbers and does not integrate with the Comms module.
Email email@example.com and provide us with the contact name, their mobile number and the student name/ID associated with them (so we can check the contact entry). We can then check for the reason the SMS failed and provide you this information.
Note: if a parent is set up for the Parents App, ScholarPack by default will automatically send an App message and not a SMS when you opt to send an SMS & App message. The logs area in Comms will tell you if the recipient received an SMS or App message and the message status.