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Sent, Delivered, Failed, Undelivered - What's the Difference?

Industry jargon tends to create confusion and at times there is just no way past it. So, for the interest of clarity, we’ve decided to help clear up some of the more useful words that relate to sending an SMS and what they actually mean. And while SMS API providers may use their own lingo to get the point across, these four terms tend to be the same for all carriers alike. 

Sent

Once the nearest upstream mobile carrier has accepted the message for delivery to the SMS network where you intend to send the message, the status is updated to “sent” (from “sending” or “accepted.”) 

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This does not mean that the SMS has reached the customer, but rather that it has reached the server of the carrier that delivers the SMS to the phone. So, in our case, this means that the operator has received the message, but it has not yet forwarded it to the handset. 

This is pretty much the last step before the SMS reaches the end-customer. The issues that may pop up at this stage are mostly related to handset issues or the phone is in roaming. If the message keeps getting stuck in “sent”, the quick fix would be to ask the customer to restart their device. 

Delivered

The service provider has received confirmation that the message has been delivered to the recipient’s phone, where available. 

This means that the carrier has sent the message to the phone, which has returned the signal stating that the SMS is received.  Then the signal gets forwarded to us. Unfortunately, detailed delivery reports are not available everywhere in the world, which means “sent” and “delivered” indicate the same thing, as handset delivery cannot be confirmed. 

Where reports are available there are still some rare cases of us getting a “delivered” status, yet the phone still not showing the messages. This can be due to a full inbox or device memory issues, so clearing the cache and restarting the device can do the trick. 

Failed

The carrier did not accept the message and delivery is not possible. 

The reasons for this may vary from missing segments (i.e., one part of a multipart SMS is missing) to operator peak time delivery issues. This does not, however, immediately show that there is anything wrong with the destination number itself.   


This usually indicates technical issues, rather than issues resulting from service misuse or incorrect phonebooks. In our case, these issues tend to be rare since Messente’s adaptive routing system helps subvert operator issues by using alternative connections for message delivery. 

Undelivered

The service provider has received a signal from the carrier indicating that the message was not delivered. 

The reasons tend to be related to the handset, destination number, or inappropriate message content (such as adult themes, gambling, etc.) The handset could be in roaming, switched off, or a landline number.   

The first thing to consider is the validity of the numbers in the database you are using and if the database has the correct format as well as mapping. Say some numbers are left with a country code and some are not, then the system can end up delivering to unintended numbers by considering the first numbers of the non-country coded number as the country code. This is one of the most common issues that pop up from time to time. 

For our clients, the best way to make sure the numbers are valid and able to receive the message is to use the Number Lookup API to check the numbers before any campaign. 

Checking the content of the message with your account manager or support team can also mitigate any potential issues in delivery. Since different countries have different regulations, sending the same content in new markets may cause issues in delivery. 

And as always, asking the customer to restart their handset is also a good way to go, especially since it is the no.1 way of solving all delivery related issues. 

Wrapping it up

The key thing here is to keep in mind that only one of these four terms (delivered) indicate that the phone received the SMS. The two statuses (undelivered, failed) relating to the message not being delivered can help figure out why messages aren’t being delivered and solve the issue before contacting support. 

If you are one of our clients, you can use the Number Lookup API to check number validity, ask your account manager for help with message content and database mapping, check statuses via https://status.messente.com/ and ask for a quick handset restart from the customer. This will cover nearly all the possible issues that may arise. 

However, if you ever need help, be sure to email support@messente.com or talk to us in our live chat on Messente.com, we’re happy to help.

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Uku Tomikas
2019-01-15 00:00:00 UTC
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