Вы можете использовать Twilio RecordSource и передать CategoryEnum как TotalPrice
$sid = "ACXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX";
$token = "your_auth_token";
$categoryEnum = "total_price"
$client = new Client($sid, $token, $categoryEnum);
В C #
TwilioClient.Init(SID, AuthToken);
DateTime currentDate = DateTime.Now;
DateTime startDate = new DateTime(currentDate.Year, currentDate.Month, 1);
var twilioPrice = (await RecordResource.ReadAsync(twilioSubAccount.SID,
category: RecordResource.CategoryEnum.Totalprice,
startDate: startDate,
endDate: startDate.AddMonths(1)))
.FirstOrDefault();