Primary phone number (E.164 format recommended, e.g. +14155551234).
phone_number_2string
Secondary phone number.
phone_number_3string
Tertiary phone number.
contact_infoobject
Arbitrary JSON metadata for the contact. Use this to store custom fields like email, address, company, or any key-value data your bot or campaign needs (e.g. {"email": "john@example.com", "company": "Acme", "plan": "enterprise"}).