Patent ID: 8290123
Filing Date: 2012-10-16
Classification: H04M

Abstract:
1. A method for detecting a communication link between a called telephone and a telephone switch by a gateway, the method comprising: (a) obtaining dialing information of the called telephone, wherein the called telephone is connected to the gateway through the telephone switch; (b) detecting a capacitance between a positive wire and a negative wire of a telephone line that electrically connects the called telephone and the telephone switch, so as to obtain a ringer equivalency number of the called telephone; (c) determining if the ringer equivalency number is equal to zero, and the procedure going directly to block (g) if the ringer equivalency number is not equal to zero, or the procedure going to block (d) if the ringer equivalency number is equal to zero; (d) obtaining a discharge curve of the positive wire and a discharge curve of the negative wire; (e) calculating a first deviation value between the discharge curve of the positive wire and a standard discharge curve of the positive wire, and a second deviation value between the discharge curve of the negative wire and a standard discharge curve of the negative wire; (f) determining if each of the two calculated deviation values is less than a preset deviation value, and the procedure going to block (g) if each of the two calculated deviation values is less than the preset deviation value, or the procedure going to block (h) if any one calculated deviation value is greater than or equal to the preset deviation value; (g) establishing a communication link between the called telephone and the telephone switch; and (h) canceling the communication link between the called telephone and the telephone switch.