Indicator Telephone Line in Use

When several people have access to the same telephone line and each has its own device, usually happen that when a call up, to the surprise is that is being occupied by another person.

The same happens when the line is used to connect to the internet is the same to be used to make a call.

To prevent such trouble to install a device to indicate when the phone line is being extencion remediation utilized by other different from ours, either by a conventional apparatus, a fax or computer modem.

Before starting the unfoldment of the project should clarify that this device works on direct telephone lines, ie they receive power from the telephone exchange. 

Good luck!!!