The professional fax server solution for Windows and Unix
Why is my 10-digit ActFax license key is not accepted by the system?
The ActFax license key format has been changed to a new format with ActFax version 4.25. The length of the license key increased from 10 digits to 20 digits. If you currently own an old (10-digit) license key and want to update to ActFax version 4.25 or newer, it is required to convert your 10-digit license key into a new 20-digit license key. Free updates for a new license are included for 2 years.
The conversion of the license key can be done at Convert License.