What do "TextPower to Carrier," "Delivery Time" and "Carrier to Handset" indications mean?

There can sometimes be confusion about what the delivery reports shown on the TextPower portal or delivered through the API actually indicate.  Many of the status messages are straightforward, such as "Delivered," but even that one requires some explanation.  

Unfortunately TextPower can't prove that a message was delivered unless the carrier says it was delivered.  What we can absolutely say however is that if a carrier says the message was delivered it definitely was.  The way it works is that the carrier waits for the handset to reply back to their system saying "I got it" and then marks the message as delivered.  Once they get that, and tell us about that, there is no disputing whether the message was delivered.

Here are some other things that you should know about these delivery reports that will help you understand them better:

1. TextPower does not create these delivery status indications.  They are sent to us by the carriers (through an intermediary called an "aggregator") and we display what they report.
2. Different carriers have different definitions and indications.  AT&T, Verizon Wireless and T-Mobile all show "Delivered" when a phone receives a message and replies back to the carrier that it has been received (although this does not mean that the message has been opened; currently no carrier supplies that information).  Sprint and the dozens of other carriers show "HP Delivered" meaning a "high probability" that the message has been delivered.  
3. If a message is not delivered the carriers will make repeated attempts for up to 24 hours. That is a maximum, however, not a minimum, as some carriers may reduce the re-try window depending on their network load.  There are fundamentally two reasons that a message does not get delivered:
1. The phone is turned off during the period when the send attempts are occurring.  Once the send attempt window has expired the message disappears and will not be attempted again even after the phone has been turned back on.
2. The phone is in an area that does not have coverage.  Coverage gaps can occur for many reasons but for many years have not been limited to distant, remote geographies like a cabin deep in the woods.  There are many modern buildings that do not yet have cellular repeaters in them and some areas, such as elevators, basements or subways, may take longer to get coverage extended to them.  
4. If a message has not been delivered and has not failed for a specific reason (e.g., the number has been "ported" to another carrier, which TextPower handles through a proprietary process described below) carriers do not send any status at all to TextPower.  Therefore when you see a "Awaiting Status From Carrier(-1)" indication in the "Carrier to Handset" field it does NOT mean that we have determined that there is no status for the message sent to that number but rather that we have not yet received any status report for that message from the carrier.  In almost every case that "Awaiting Status From Carrier" message will change because the message is eventually delivered.  It may take a few minutes, an hour or several hours until the message is delivered and the carrier gets the response back from the mobile device confirming that and then more time until the carrier relays that status to us.  As soon as they do the "Carrier to Handset" status will change from "Awaiting Status From Carrier" to "Delivered" or "HP Delivered."  If the message is not delivered within the 24-hour retry window (subject to modification as described above) then the "Carrier to Handset" message will NOT change.  It will remain as "Awaiting Status From Carrier" because the carrier has not provided TextPower with any updated status.  
5. The differences in times that carriers will send TextPower the delivery status of a message varies widely and is affected greatly by time of day, carrier and network load.  You can see the average carrier delivery report delay on the Messages>See Sent Msgs page of the customer portal.  If you refresh the page you will see that the average delay changes significantly even with only a few seconds difference.  Our algorithm calculates the messages that have been sent through the system, the time it takes to get delivery reports on them, how many have not yet received delivery reports and a lot of other data to determine this delay and it reflects the changes in near-real-time.

Carriers prevent automated retries of messages that are in the pending "Awaiting Status From Carrier" state.  If you send another, separate message during this time period it will also be delivered and thus your end user will receive two identical messages.  We recommend strongly that you do not send a second message as it causes significant dissatisfaction and complaints from people who receive duplicate messages.