Attempted: number of recipients who fit the criteria for the message

Sent: number of recipients where the message is sent to the SMS network. To be eligible they must not be opted out and have a valid mobile phone number. 

• Number of segments sent is used for per segment billing
• If messages are considered ‘Failed’, it will not be calculated into ‘Sent’

Delivered: number of recipients whose phone carrier accepted the message(s)

• If messages are not accepted they will be considered ‘Undelivered’

Click here to learn more about why messages are considered "Failed" and "Undelivered"