SMS delivery failure: What is it and why does it happen?
Published on February 27, 2024
SMS delivery failure happens when a text message fails to deliver to the intended recipient. This can happen for several reasons, and understanding these causes is important for troubleshooting and improving message delivery.
1. Network issues
One common reason for SMS delivery failure is problems with the carrier’s network. These could include temporary outages, poor signal coverage, or issues with SMS gateways. If the carrier’s infrastructure is unavailable or overloaded, it can prevent the message from reaching the recipient’s phone.
2. Invalid phone number
If the phone number is incorrect, incomplete, or no longer in service, the message will fail to deliver. This might include mistyped digits, deactivated numbers, or numbers that are not capable of receiving SMS (e.g., landline phones or numbers outside the supported region).
3. Recipient’s device
The recipient’s phone may be set to block SMS from unknown senders, or their device may not support certain types of SMS messages (e.g., multimedia or longer texts). In some cases, if the recipient’s device is out of battery or turned off, the message may fail to be delivered until they are back online.
4. Carrier restrictions
Some carriers may impose limits on SMS delivery based on factors like the type of message (promotional vs. transactional) or the sender’s reputation. High-volume senders might also be subject to restrictions if they violate spam rules or send messages to invalid numbers.
5. Short message service center (SMSC) delays
The SMSC is responsible for routing text messages to recipients. If the SMSC experiences delays or is congested, it may result in failed deliveries. The message could be stuck in the queue until it is eventually delivered, or it may be discarded if the delay is prolonged.
6. Blocked numbers or spam filters
If the sender’s number has been flagged as spam by the recipient or their carrier, messages may be blocked or filtered out, causing delivery failure. This is particularly common with marketing messages sent in bulk.
Addressing SMS delivery failures typically involves checking the sender’s configuration, verifying the recipient’s phone number, ensuring the carrier’s network is stable, and adhering to local regulations to avoid filtering or blocking.
If you need help with your SMS deliverability, reach out to our team of experts.