What are the reasons for message failure?


There are a number of reasons why a message may not be delivered immediately, ranging from operator and country restrictions to a handset being unable to receive content.

Here’s an abbreviated list of reasons why A2P SMS may fail to reach the end-user. If none of the reasons below provides a clear answer to why your text message was not delivered, please get in touch at support@tyntec.com.

SMS spam control

Many mobile operators across the globe are governed by regulations to control spam, blocking A2P messages due to senderID or content restrictions (especially promotional content). In some markets, filtering technology is used to keep out unwanted text messages. These filters, however, are not perfect and can lead to filtering legitimate SMS traffic. Some filters even send back a fake handset delivery confirmation.

Roaming

Unfortunately tyntec cannot ensure delivery to roaming numbers due to the complexity and lack of reliability of Carrier Interconnection Agreements. Basically, this is related to the routing carrier not having Interconnection Agreements with the roaming operator.

Handset issues

There are a number of issues that can prevent a phone from receiving an SMS that it would be able to receive under normal conditions, including the phone being out of reach, being switched off for 48 hours, having a full memory, roaming, a temporary disconnection, the number not existing anymore, and so on.

Incorrect data

A2P SMS delivery is impacted by incorrect data such as unknown subscriber, numbers formatted incorrectly, receiver number not in international format, prefix unknown or landline prefix and more.

To avoid these issues, make sure you enter the phone numbers in international format (E.164) and verify the validity and accuracy of the phone numbers with our Number Verification API.

Wrong content in messages

Not all phones support all languages. For instance, a message in Mandarin sent to a French phone will arrive but will not display properly. Sending binary messages to an iPhone won’t work either. Certain carriers also filter some keywords (such as the carrier’s own name) to prevent brand theft and scams.

Lack of coverage

Even with our unparalleled reach, there may be networks that tyntec does not have connectivity to send messages to. Prior to sending your business SMS messages, check whether we cover your required destination. In case we don’t, please contact your account manager, as we may be able to source that destination for you.

Portability failure

Every day, a lot of phone numbers get ported from one network to another. The number will still look like the original network but the actual network will have changed. To address this, carriers and A2P SMS providers like tyntec have introduced network lookups — such as our Number Verification API — that provide the real network before a message is sent. This guarantees that the SMS is routed correctly. The process, however, is not perfect. Some carriers, still don’t support these number looks-ups. Additionally, some portability databases only get updated every 24 hours.