There is no service out there that is 100% accurate. Millions of numbers change hands every year in the United States and records updating can't keep up with it. This became even more prevalent with the proliferation of VOIP numbers; these days changing a phone number is almost as simple as changing a pair of socks.
Reachable Line Status*: This service offers a low-cost method of identifying phone numbers as reachable or not (active/disconnected). The method is based on sophisticated algorithms and carrier data. The service works for US only. These statuses are returned:
- ACTIVE - Number is reachable
- INACTIVE - Disconnected number
- INVALID - Phone number does not exist (e.g. invalid area code or not issued)
- UNKNOWN - Status cannot determined
*Accuracy. Some active numbers may be reported as inactive, especially if they have been issued or reissued within the last 60 - 90 days. Phone number accuracy can vary due to how old the numbers in your list are, where they were derived, line type, and regional or national carrier reporting. It's not uncommon to see a 5% - 15% variance in reporting active as inactive or vice versa. Lists obtained via number generator or other means have greater degrees of variance.