Extension phone off-hook check for Type 2 Caller ID reception in a telephone adjunct device

摘要

A system and method for detecting a condition of an extension telephone is presented for processing caller ID information. A reference value of a telephone line connected to an apparatus is first determined. An auxiliary telephone connected to the apparatus is then disconnected. A second value of the telephone line is determined while the auxiliary telephone is disconnected. The reference value and the second value of the telephone line are compared to determine the condition, such as off-hook, of the extension telephone.