The 'authenticate' error could typically show up when a subaccount has not been used for a long time, as Twilio resets the credentials automatically.
Example: If you have signed up like a year ago but never used Twilio services, in this case, Twilio resets the credentials / deactivates your phone services since you have not used it for a long time. This measure is taken for security reasons.
Please contact us at [email protected] and we will get this resolved for you.
Note: Existing Twilio Numbers are currently not supported with our Native Integration. You can either purchase a number through the available numbers in the search, or add a personal 'mobile' number.