Extension-based Recording Solutions

Here a tap is placed on each extension that should be recorded. So it is possible to selectively tap only some phones in an organization. However, phones and phone links are often vendor specific and the technical standards for these are not published or only available to partners of the phone system vendor. So compatibility to system phones can not be achieved in all cases. The last option in this case is to tap the receiver/handset/headset cable, which does only carry the audio signal without any additional signalling information.

Diagram: extension based recording


  • Selective tapping of only some phones easily possible.
  • Extension information is always available.
  • Recording of both internal and external calls for this extension.
  • Low cost for recording just a few extensions.


  • System phones often use vendor specific protocols, there are compatibility issues.
  • Tapping a large number of phones becomes expensive (lots of recorders needed), does not scale well to large channel counts.
  • A central storage of recordings might be hard to implement (EyeSDN software offers a collector function to achieve that).