An apparatus, system, and method for enabling multi-frequency communication over a telephone network having a billing/tax tone are disclosed. The apparatus comprises a connection port operable to couple to a telephone network. An output port is coupled to the input port, and is operable to couple to...http://www.google.com.au/patents/US6674843?utm_source=gb-gplus-sharePatent US6674843 - Apparatus system and method for enabling multi-frequency communication over a telephone network having a billing/tax tone
