Top 5 Reasons Why Your SMS Delayed or Not Delivered

Mar 03, 2018
Text Messages Delayed

The delay or failure of SMS messages delivery may impact on your business. This will have a terrible impact on your marketing and business efforts. While individual and bulk message deliveries may have different reasons for delay or failure, there are some points that are common for both.

The top 5 reasons why your SMS is delayed or not delivered.

5 reasons why SMS is delayed


SMS messages may be delayed if you are out of the network coverage area. Messages may also be blocked because of mountains. Another reason is driving at a speed above 50 km/h.

Network Traffic

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

Issues with a Mobile Device

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

Error on the Operator’s Server

Another reason for SMS messages delays is an error on the operator's server. Normally such problems are easily fixed by the carriers and there is a low probability of message loss.

Different Networks

If sender and 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 is 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 for that, including queue overflow, suspended account, unreachable destination handset, unknown destination handset. “Queue overflow” means that you tried to send too many messages quickly and your message became overflowed. In this case, Twilio suggests sending the message again after waiting some time. “Suspended account” means your account was suspended between the time messages were sent and delivered.

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

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 a long time and the waiting time elapses, the message will expire. Even if the owner gets back to his phone after some time, the messages will not be delivered after the expiry time. 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.

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 numbers. When you send messages and the network tries to deliver it but finds no synergy between the network and the number, then the message gets lost.”

The Number is in Roaming

Problems may occur if the number you are sending SMS is not in the country. When the mobile device is in roaming, the delivery of messages is not guaranteed.

Carriers Filters

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


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 delivery failure. 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.

Contact your network provider if you cannot solve the issue.

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