2036: Outside customer window.

HTTP status: 422. May also be reported as a field-level finding in error.details[].

Only an approved template part may be sent when the customer’s 24-hour window has lapsed or never opened. Nothing was sent.

• Read error.context.expires_at: a timestamp means the window lapsed, null means the customer has never messaged this number.
• Send a template part, or wait for the customer to reply, which reopens the window.

• Sending messages guide
• Templates guide