If you have access to a Corporate/Volume License ISO of Windows XP Professional, you can use a valid VL key. These versions do not require a connection to Microsoft to "phone home" for activation.
Third-party "KMS Activator" tools for Windows XP are unofficial, non-Microsoft scripts that attempt to bypass the Windows Product Activation (WPA) system. Below is a technical summary of how Windows XP activation works and how modern workarounds are currently handled. Windows XP Activation Methods Retail/OEM Activation kms activator windows xp professional updated