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Live Speaker Detection

Live Speaker Detection allows you to classify whether the number you're calling is answered by a human, answering machine or fax machine. That's useful if, for example, you want to ask someone a question or, if they're out, leave them a message.

Live Speaker Detection is commonly referred to as Answering Machine Detection (AMD). In the REST API, we call it Far-end Classification. Whichever term is used, they're one and the same thing.


The Live Speaker Detection timeout is the longest you're prepared to wait for it to classify. The maximum value is 5000 msec. That gives the best results and, unless the country you're dialling has a shorter legal restriction, it's generally the best value to use.


There are three Live Speaker Detection modes:

  • Default
  • Network Connect
  • Answer Detect

The REST API always uses Default mode - its Live Speaker Detection is not configurable.

The UAS uses Default mode unless you specify a different one and, in most cases, Default is the best mode to use.

Default mode

If you're dialling through Aculab's outbound PSTN provider, Default mode chooses the best mode based on the country code of the number you dial. Otherwise, it assumes the best mode based on the Cloud you're using - Network Connect for the EU Cloud and Answer Detect for the US Cloud.

Network Connect and Answer Detect modes

These modes are explained in the tabs below.


Our Live Speaker Detection has been extensively optimised using a large set of data and performs well on high volumes of calls every day. However, please note that, due to the huge variability in audio content on answered calls, this task inherently cannot provide complete accuracy.