13112: Annotate: Invalid nested element

This warning is raised when <Annotate> contains a nested element other than BillingReferenceTag. Use only BillingReferenceTag inside <Annotate>.

• Your TwiML nests an unsupported child element inside <Annotate> instead of BillingReferenceTag.
• The nested element name is misspelled or uses incorrect casing. TwiML element names are case sensitive.
• Your application generates TwiML dynamically and inserts extra XML elements that <Annotate> does not support, because Twilio only accepts specific TwiML verbs and nouns during parsing.

• Update your TwiML so <Annotate> contains only BillingReferenceTag.
• Remove any other nested TwiML or custom XML elements from <Annotate>.
• Verify the spelling and casing of BillingReferenceTag before you return the TwiML response.
• Generate your TwiML with a Twilio helper library when possible. This can help you avoid invalid XML structure.

• TwiML for Programmable Voice
• Programmable Voice API Overview
• Troubleshooting Twilio