The delivery of SMS messages is not as simple as it seems. When sending long text messages over 160 characters, the message needs to be split into multiple fragments before being sent, which can lead to out-of-order messages being received by the end user. To solve this issue, developers can use a feature called inbound concatenation, which automatically reassembles the fragmented message and sends it in the correct order. Twilio offers an auto-assembly solution for inbound concatenation, allowing developers to send long messages without requiring additional code or UDH logic, making it easier to build SMS applications with reliable messaging capabilities.