The RND API may be used to scrub your lists to determine if a number has been disconnected or is still assigned to the consumer that you intend to contact.
From the FCC:
"The FCC's Reassigned Numbers Database (RND) is designed to prevent a consumer from getting unwanted calls intended for someone who previously held their phone number. Callers can use the database to determine whether a telephone number may have been reassigned so they can avoid calling consumers who do not want to receive the calls.
Callers that use the database can also reduce their potential Telephone Consumer Protection Act (TCPA) liability by avoiding inadvertent calls to consumers who have not given consent for the call."
"Callers can check before making a call to find out if the phone number may have been reassigned. If the database wrongly indicates that the number has not been reassigned, the caller may be protected against TCPA liability when placing the call."
Note that the RND database is updated once monthly no earlier than the 16th of the month and no later than 8am EST on the 17th of each month. As an example, if you query a number on the 18th of the month, you may use the results of that query until the next database update occurs.
The following headers are required:
Authorization: Bearer (followed by your existing API key)
X-Account-Id: {your existing AccountId} - the same one that is currently required in the JSON payload when sending a message
Content-Type: application/json
*** In case you have multiple accounts/Pronto account numbers, you'll want to use the appropriate AccountId for each query in order to have proper Safe Harbor protection and so that RND queries can be associated to the correct account for reporting and billing purposes.
The JSON body is pretty simple: tnList is an array of numbers to query (maximum 1000 numbers per array/API call), each with:
"tn" - the telephone number to query
"date" - the most recent date of consent that you have for the number
"companyId" - your RND company ID will be provided by Pronto once registration has been completed for your company
"referenceId" - Optional. If supplied, the referenceId is saved with each number and visible within our billing dashboard and is returned to you in the results...
{
"tnList": [
{
"tn": "3035551212",
"date": "2025-10-31",
"companyId": "RND company ID provided by Pronto upon completed RND registration",
"referenceId": "optional reference ID"
},
{
"tn": "7201586363",
"date": "2025-10-31",
"companyId": "RND company ID provided by Pronto upon completed RND registration",
"referenceId": "account123"
}
]
}
And the response:
{
"results": [
{
"tn": "3035551212",
"dateProvided": "2025-10-31",
"disconnected": "no",
"companyId": "RND company ID provided by Pronto upon completed RND registration",
"referenceId": "optional reference echo'd back to you"
}
],
"errors": [
{
"index": 2,
"tn": "7201586363",
"date": "2025-10-31",
"errors": [
{
"field": "tn",
"message": "Phone number must follow NANP format (positions 1 and 4 must be 2-9)"
}
]
}
],
"summary": {
"total": 2,
"valid": 1,
"invalid": 1,
"billable": 1
}
}
You'll notice that the response may include "errors", in the example above, the second telephone number provided in the request is invalid as described in the errors...