Top Flutter SMS packages SMS stands for Short Message Service and is a form of communication that allows users to send short text messages to other mobile phone users. SMS messages are typically limited to 160 characters, making them ideal for time-sensitive, short, quick messages. For example, sending one-time-passwords (OTPs) to complete a financial transaction. The complete list of Flutter packages that can read and write SMS, read and autofill OTPs and perform SMS based authentication is provided below.