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​Line Echo Cancelation – IP to analog conversations

DSP resources and call capacity
By default the echo cancelation time is set to 5 msec. In many cases this is sufficient. The DSP has in that case enough capacity to service 10 simultaneous calls between IP on one side and an analogue intercom or telephone on the other side.

Especially some telephones need a longer cancelation time, even up to 15 msec. The number of simultaneous calls then drops to 3.

LEC setting versus call capacity:

  • 5 msec ßà 10 calls
  • 10 msec ßà 6 calls
  • 15 msec ßà 3 calls

The cancelation time can be set from the TST-console. Navigate to:

  • ex_profile.timeouts.lec_time = 5 (0x0005)

and change the lec-value as required.

Note that when the DSP resources are exhausted the AlphaCom will simply set the call to voice switched duplex. The call can therefore still be established but it will not be full duplex.