Twilio's Alphanumeric Sender ID feature allows businesses to send personalized SMS messages with a customized sender name, increasing open rates and reinforcing brand identity. This feature is only available for upgraded Twilio accounts and is supported by certain countries, including those that require registration. Leveraging an alphanumeric sender ID can improve message delivery quality, reduce carrier filtering of A2P traffic, and strengthen brand recognition. However, there are limitations to its use, such as non-response capabilities and regulatory compliance requirements, and certain countries have specific rules and fees associated with its usage. To set up the feature, users must complete three steps: enabling it in their project settings, checking support for the feature and registration requirements, and defining their alphanumeric sender ID according to Twilio's guidelines.