This modem driver was originally developed by Dell for use in their systems. It is perfectly compatible for the Compaq 7xxx series---the HP 56 K modem by PCTEL was purchased by CONEXANT, who in turn was purchased by Microsoft. You may use this driver as long as you agree to boycott Hewlett-Packard as long as you live. HP acquired Compaq, aND REFUSES TO SUPPORT THEIR PRODUCTS, even though they still produce under the Compaq name! I invite the lazy a***s from Fiornas crew to challenge me! Get with customer service you jerks! I will post drivers on this website as long as you agree to BOYCOTT HP! ___> )<___ T.