You will need
  • The telephone support DTMF mode
The extension number can be dialed only if the phone moved from pulse mode to tone. To do this, simply press the asterisk (*). For most phones this method works. If your phone is translated in a tone mode in a different way, find out how to do it in the instructions.
The most common way to enter the extension number, call the main number, wait for a response from the PBX, and then enter the extension number. Most often do so. This method always works.
Another way that might work, if your phone has a pause button enter the number. In this case, no need to wait for a response from the PBX system. Dial main number, then press the pause symbol, you can then enter the extension. Pause may be indicated by the symbol "P".
But not all PBX companies that require the introduction of extensions, and support the pause symbol, even if it is on your phone. Some calling will greet you and then force you to listen to the text. To enter the extension number you can, only allowing the answering machine to fully speak. Usually at the end of the speech you may hear something like: "...Wait for the operator's response or after the tone, enter the extension number. Should the signal, and you can now enter the extension number. All characters entered before the signal, this PBX will be ignored.
On some phones there is a button "Flash", which provides access to the functionality of the PBX. But then again, not all exchanges support this button. To enter the extension number, press Flash, then dial the desired additional numbers.
You can simulate the button action in Flash, if very briefly and quickly hit the lever. This method may work for some phones but not all. Some will sever the connection, and the other will allow you to enter the extension number, without waiting for the response of the system.