Howto:Having ECHO problems

Applies To

This information applies to

• all innovaphone products

any build

FIXME: has to be updated and corrected

More Information

If you have an echo problem – pleas check this first:

Do you meet the Echo problem always ?

• between IP phones ?

• between Isdn and IP phones ?

• between analog phones and/or Dect phones to IP phones or Isdn (connected an analog adapter IP21,IP22,IP24)?

IF this problem is with analog or Dect Phone - they have no good jitter buffer - occurs with very old Dect phones in very few cases - the best solution here is - eliminate this phone.

If you have a general echo problem - you have a delay Problem in your Network

To find this out

Pleas watch PBX – Call screen (administration - pbx - calls)

Extension A  NameA H323EFC:TRANSIT G729AB (42,6,3)  >> Extension B NameB H323EFC:TRANSIT G729AB (47,2,5)  Connected 

The explanation for that screen is here Reference:Administration/PBX/Calls

The values in the brackets are

Round trip (RT) = Transit time of a data packet from A to B and back again.

Jitter = Latency time (time interval from the end of an event up to the start of the response).

Loss (PL) = Number of lost packets (packet loss).

Jitter

If the jitter is greater that 20 – the echo compensation does not work – normal is the jitter is less that 5ms.

If the jitter is greater then 5ms – please check your network – switch off flow control and buffers – real time protocols don't like this – if you have routers and different bandwidth in your network – switch on RTP priority or configure an TOS value on the Phones and prioritize this traffic.

General Codec information

Use G.729 60ms WAN (default value)

– pros: optimal bandwidth – tolerates packet loss

– contras: “subjective” turns the volume down – please correct via -> button on the phone

Use G.711 20ms for LAN

- pros: like ISDN – echo isn’t audible - “subjective” turns the volume up

- contras: sensitive if you have packet loss – bandwidth intense

Echo Canceller

We support the The G.168 Echo Canceller on all our product with am maximum of 24ms jitter.

You can Disable the Echo canceller but no adjustments to set- it is default enabled.

Our echo compression is dynamic - contend sensitive -. no values to set.

It is no solution to make volume adjustments on the Endpoints for solving the Echo problem