Practices of telephony




PTR (Point of Completion of Network)

It protects against surges not to damage to the equipment and incorporates a mechanism of test of failures to determine if a failure is in the inner installation of the user or in the network of the operating company. Next are two commercial examples:

PTR Telef³nica

PTR Krone

Rosette or Base of Access to Terminal (BAT) of surface

It is the element where the telephone terminal is connected. Inner conexionado Su one is in the following figure:

Terminals of a surface rosette

The telephone pair is due to connect to the terminals red and green without concerning the polarity. These correspond both to central contacts of the connector (it is possible to be verified measuring continuity with pol­metro).



To mount in the board of practices the scheme of the drawing. In him the three rosettes are in parallel, which means that all the telephones will sound simultaneously and will be able to be spoken simultaneously by all, superposing the voices.

1. - To connect the line to the PTR by means of a cable that in the other end goes united to the rosette of telephone of the factory with a connector RJ11.

  • To cut to a cable of telephony of about 40 cm and to connect by means of the crimpadora a connector to him RJ 6p2c or 6p4c in an end. To consider that the threads that carry the electrical signal of the line are due to connect to the central contacts of the connector.
  • To peel the insulator of threads of the opposite end.
  • To open the PTR and to connect the cable to him realised in the previous step in the terminals of corresponding entrance of line, according to the following figure:

  • To fix the PTR to the scale model, screwing it by the corresponding orifices:

2. - To connect the rosettes to the PTR:

  • To lie down by the canal the telephone cable between the rosettes and the PTR, realising a connection in parallel between the rosettes according to the following figure:

  • On the other to connect cables to the rosettes (terminal power stations) by an end and to the PTR, according to the figure:

3. - To verify the operation of the assembly.

  • It connects the telephone line to the PTR by means of the cable realised in the first step.
  • It verifies the operation of the three rosettes by means of the use of telephones connected to the rosettes and verifying that they have invitation tone to mark.



1. - It explains how it is the cable that you have used actually (number of threads, protection, color)


2. - What functions fulfill the Point of Completion of Red (PTR)?

Why it serves the sliding eyelash that it has?

What cables go connected to the PTR? With what letters they are identified in the device?


3. - Which is the function of the rosette or BAT?

What type of connector is used to insert in her?

In a basic line, how many are threads connected to her and in what terminal?

Which is the maximum number of rosettes that can be installed inside a house to assure that the laying of the line works well?


4. - Be realised independent can calls from the different rosettes? It indicates why.


Now we are going to study, once we have the finished installation of home, what tension has the telephone line, and for it we are going to follow some steps, that we detailed and responding to each one of the questions that are formulated

1 In rest (without offing-hook), to measure with pol­metro the tension that has the line of telephone. We will call it Vr

2.  To do the same but offing-hook the telephone. We will call it You

3. Now, to say to some companion who calls to the fixed telephone and to measure the tension. To this tension we will call it Vll

4. Using an oscilloscope now, to repeat steps 1 to 3 and to verify if they exist component alternating

5. What happens if the threads of the telephone change?

6. It realises a project to obtain light in emergency, using the line of telephone, in case of having a cut of the electricity provision.