Profile: Sparrevohn Engineering produces telephone related products. We provide fone alone, and fone filter products that can be used with the computer. Our fone alone is a device that will automatically disconnect the answering machine/ computer modem from the phone line, any time that another phone on the same line is taken off hook. It can also be used as an automatic exclusion device. Our fone filter is a way to eliminate radio frequency interference. When it is connected to the telephone, it allows only the normal voice frequencies to get through to the telephone, and all other frequencies are filtered out.