Patent ID: 6661850
Filing Date: 2003-12-09
Classification: H04L,H04M

Abstract:
An interface testing system for use in transmitting data within a voice band, the interface testing system comprising:an exchange for transmitting information including a caller number to a subscriber line circuit, to which customer premise equipment is connected through a telephone line; a caller line identification transmitter provided in the exchange for transmitting a frequency shift keying signal which is modulated with the transmission information including a caller number; a loop circuit attached to the exchange for turning back the frequency shift keying signal output from the caller line identification transmitter so as to imitate a loop of a subscriber's telephone set, which is connected to the customer premise equipment; and a firmware provided in the exchange for receiving a the frequency shift keying signal turned back from the loop circuit and controlling to open and close the loop circuit according to testing of an On-Hook or Off-Hook protocol to judge the normality of the frequency shift keying signal.