### How this function works Use this function to get information about the phone number of a carrier or caller. The function will be triggered by a document written to a specified Cloud Firestore collection. The document must contain the phone number and lookup type. ### Prerequisites - You must have previous knowledge of **Firestore**. - You must have previous knowledge of **Twilio**. ### Function details In order to complete the installation process, you must add the required info to the form with the following parameters from your Twilio account: - TWILIO_ACCOUNT_SID: The Account SID, a unique key that Twilio uses to identify the user. - TWILIO_AUTH_TOKEN: The token to grant access to Twilio services. - PHONE_NUMBER_ACCESSOR: The name of the field in the Firestore document that will contain the phone number. The following is an example of how to use this function with `phoneNumber` as the name of the PHONE_NUMBER_ACCESSOR field: ``` { phoneNumber: '+15108675310', lookupType: ['carrier','caller-name'], } ``` Whenever you write a document to the specified Cloud Firestore collection, this function does the following: - Retrieves additional information about a phone number using Twilio Lookup API. - Adds the additional information about a phone number to a separately specified field **lookupResponse** in the same document. The **lookupResponse** should appear in the document with the following structure: ``` lookupResponse: { "caller_name": { "caller_name": "Delicious Cheese Cake", "caller_type": "CONSUMER", "error_code": null }, "carrier": { "error_code": null, "mobile_country_code": "310", "mobile_network_code": "456", "name": "verizon", "type": "mobile" }, "country_code": "US", "national_format": "(510) 867-5310", "phone_number": "+15108675310", "add_ons": null, "url": "https://lookups.twilio.com/v1/PhoneNumbers/+15108675310" } ``` >Note that if the **phoneNumber** or **lookupType** of the document is updated, then the information will be automatically updated, as well. ### Resources For more information about Twilio, see: - [Twilio Lookup API Documentation](https://www.twilio.com/docs/lookup/api) - [Twilio Support](https://console.twilio.com/?frameUrl=/console/support)