Proxy Public Beta is currently closed for new customers. Please consider using Twilio Conversations and Programmable Voice directly if you are building your masking application.
Note that this does not have any impact on Twilio Flex customers.
Twilio's Proxy API is currently available as a Public Beta product. Some features are not yet implemented and others may be changed before the product is declared as Generally Available.
Public Beta products are not covered by a Twilio SLA.
By default, Twilio handles opt-out and opt-in keywords as described in Twilio support for opt-out keywords (SMS STOP filtering) document; when Twilio receives an opt-out keyword from an external sender phone number to any Twilio number, Twilio will reply with a pre-generated response and will no longer send messages from the Twilio Number to that external phone number until the sender opts back in by sending an opt-in keyword.
When using SMS with Proxy, there are special considerations and deviations from the standard handling of opt-out and opt-in keywords: