The delay or delivery failure of SMS messages may impact on you and your business. This may have implications both for your personal life and your marketing efforts. While individual and bulk message deliveries may have different reasons for delay or failure of delivery, there are also reasons that are common for both.

Here are the top 5 reasons why your SMS is delayed or not delivered.

5 reasons why SMS is delayed

  1. Coverage:

    SMS message may be delayed if you are out of the network’s coverage area. Messages may also be blocked because you are in a mountainous area. Another reason is driving at a speed above about 50 km/h.

  1. Network traffic: 

    Heavy traffic may also be a reason for message delay. Some periods of the day create heavy congestion on the network carrier and this may delay the message delivery.

  1. Issues with a mobile device:

    The delay of SMS messages may just be connected with your personal mobile phone. There is a possibility that your inbox is full of messages or message application is frozen.

  1. Error on the operator’s server:

    Another reason for the delay of SMS messages is an error on the operator’s server. Normally such problems are easily fixed by the carriers and there is a low probability that your message will be lost.

  2. Different networks: 

    If the sender and the receiver use different networks, there is a probability that the messages will be delayed since each network prioritizes its own traffic.

5 reasons why SMS not delivered

SMS messages may not only be delayed. There is a possibility that they may not be delivered at all. Twilio lists at least 9 reasons why messages may not be delivered, including queue overflow, suspended account, unreachable destination handset, unknown destination handset, and some others. “Queue overflow”, for example, means you tried to send too many messages too quickly and your message queue overflowed. In this case, Twilio suggests sending the message again after waiting some time. “Suspended account” means your account was suspended between the time of message send and delivery.

While the reasons for SMS delivery failure are many, we will try to focus on the most common 5 reasons why SMS messages may fail to be delivered.

  1. Your phone may be switched off for a long time:

    Normally, SMS messages have to wait time for the phone to come back. If the phone stays off for long and the waiting time elapses, the message expires. Even if the owner gets back to his phone after some time, the message will not be delivered after the expiry period. The same happens when your mobile device is out of network coverage for a long time. Whenever the phone comes back on, the owner will not get the message because of delivery time expiry.

  1. Ported phone numbers may be the reason for SMS delivery failure:

    According to Smart SMS Solutions, ported phone numbers may be a reason for SMS delivery failure. The article says “The reason for this has been attributed to the fact that these network providers and the NCC do not have an updated database for these numbers. When you send your messages and the network tries to deliver it but finds no synergy between the network and the number, then the message gets lost.”

  2. The number is in roaming: 

    Problems may be caused if the number you are sending SMS is not in the country. When the mobile device is in roaming, the delivery of your message is not guaranteed.

  3. Carriers Filters:

    When it comes to bulk messages, some carriers block A2P messages or bulk messages sent by SMS vendors. This is done in an attempt to prevent spam, unwanted messages, phishing attempts. By contrast, P2P messages, or messages between individuals, are likely to be delivered without any filters.

  4. Routing:

    According to DialMyCalls, “While most SMS messages are sent through routes directly to the relevant phone number, this is not always the case. Some SMS messages may be sent to a particular network provider that does not allow the delivery of a message. If that network provider does not provide automatic rerouting services, the delivery of the message may fail entirely”.

Bottom line

They are dozens of reasons why messages may not be delivered or may be delayed. Network providers usually come up with a report in case of message delay or failure to deliver. We have come up with some of the most common reasons for such happenings.

Heavy traffic on the carrier’s network, some issues with the mobile device, different networks, and error on the operator’s server are most common for message delay.

The messages may be lost due to the phone being switched off for a long time, ported numbers, the number is in roaming, carriers filters, and routing.

Contact your network provider if you cannot solve the issue.