We are using Zoho bookings integration, and we want to kadd a validation for the phone number, to ensure it is a valid one. There is no documentation about what is considered a valid phone number in https://www.zoho.com/bookings/help/api/v1/book-appointment.html . I found a regular expression for phone validation in here: https://www.zoho.com/crm/developer/docs/api/v2/insert-records.html, but this seem not to be the one used in Zoho Bookings, as it there are errors raised even though this regex is valid. Where can I see what it used to validate a phone number in the book appointment endpoint? This information should be available in the endpoint documentation.