Abstract: In an Internet phone interface card having a sound function, an Internet phone interface card having a sound function including a telephone signal detector detecting a state change signal transmitted from a general telephone, a signal processing unit receiving a telephonic signal from the telephone connected to a LAN (Local Area Network) or the Internet and transmitting a telephonic signal having a sound level adjustable to listening of a user to the general telephone, a ring signal generator detecting a telephonic signal from the LAN or Internet, generating a ring signal and transmitting it to the general telephone, and a microprocessor controlling the each circuit unit is capable of always providing an optimum sound level to a user although it is connected to other external telephone and providing an optimum sound level to the user in telephonic communication even after using other sound functions by setting a user request sound level by performing telephonic communication with a general telephone or an Int