SMS Call Results can take a variety of sequence paths depending on a number of factors. Some of these factors are recipient dependent (example: recipient confirms message) and some are carrier and/or SMS Operator dependent (Figure 1 on the right shows a high-level representation of this). As a result, there is no discrete sequence that SMS Call Results will follow every time.

Some important things to keep in mind with SMS Call Results:

1. Call Results that are Carrier and/or SMS Operator dependent include the following:
   1. Delivered – To Carrier
   2. Delivered – To Handset
   3. Not Delivered – Invalid Number
   4. Not Delivered – Downstream Communication Error
   5. Not Delivered – Carrier Expired
   6. Not Delivered - Carrier Rejected
2. Call Results that are Sender-dependent include the following:

1. Not Attempted- Invalid Path
2. Not Attempted- Throttling Time Exceeded
3. Not Attempted- Inactive Path
4. Not Delivered- Duplicate Path
5. Not Delivered- Notification Expired

3. Call Results that are Recipient-dependent include the following:

1. Confirmed
2. Confirmed by Call Back
3. Not Attempted- Email Preferred Over SMS
4. Not Attempted- Unsubscribed

4. Call Results that are carrier and/or SMS Operator dependent are only available if a "delivery receipt" is provided to Everbridge by the carrier and/or SMS Operator. Not all carriers and/or SMS Operators support delivery receipts.
5. Carriers and/or SMS Operators may support delivery receipts at different levels. For example, some carriers send delivery receipts indicating they have received the message, but do not send delivery receipts indicating that the message has been delivered to the handset — even though it may have been. A Call Result not showing delivered to handset is not always indicative of the message not having been delivered to the handset.
6. If supported by the carrier and/or SMS Operator, the “Not Delivered – Carrier Expired” Call Result will take 24 hours to be sent to Everbridge and show up as a Call Result. Until then, the message will continue to show with a Call Result of “Sent”.
7. There are over two-thousand mobile carriers around the world; Everbridge does not maintain a list of which carriers support delivery receipts and at what levels, nor can we investigate carrier support for this functionality since carriers may change their infrastructure and support for any feature ad hoc without notice.