Echo issue Voice over IP urgent

[satishmothukri]

Hi ,

Most of the users are  facing echo problems when they are talking to other users belonsg to different location.Below is the setup of the netwrok.   

<----------- LOACATION A ---------------------->                                        <------------------- LOCATION B ----------------------------->

IP telephone --- 3750 Switch --- 3845 router  ------- MPLS cloud  -------- 3845 router ------ Brocade switches  ----- Ip telephone .

QoS is configured on 3750 switch and 3845 router of Location A and 3845 router of Location B router to prioritize voice traffic.

Phones of location A would contact Audio Codec for siganling placed at Location B.Most of the users sitting at Location A are experiencing Echo issues while talking.

Can anybody through some light on this issue ..What might be causing echo issue.

Thanks ,
M S K       

[paolo bevilacqua]

What exactly is "IP telephone", on both sides ?

[satishmothukri]

Hi Paolo ,

Ip telephone is nothing but polycom phone connected to switches which gets ip address fromDHCP server placed in the LAN.

Thanks ,
M S K

[paolo bevilacqua]

Network (IP, switches, routers, MPLS) does not cause echo. You will have to work this with the phones vendor.

[Robert Thomas]

Hi,

Listen carefully to a recording of the issue reported, there are multiple audio issues that could be mistakenly reported as Echo, like "under watter sound", jitter, clicking... and others.

Echo per se is caused by an impedence mismatch on the Electrical signal, when the call goes back into a Analog Circuit, like an FXO line. You should not have echo between two IP Phones where everything is VoIP.

Most Echo scenarios are presented on PSTN calls, and require either Echo cancellers, or to adjust the gain on the FXO lines.

Keep in mind there's also local and remote echo, does the user heard back himself, or the remote person having the echo?

[satishmothukri]

Hi Robert ,

Thanks for your inputs.Users were hearing back their voice whenever they were speaking to other location users.Audio codec present at Location B only . Location A users uses Audio codec ( G.711) placed at Location B for compression and de-compression of Audio.

Voice team is suspecting full / half duplexity issue over the WAN.We have checked the duplexity with service provider and every thing is fine as per duplex is considered.

Need to idetify root cause for Echo issue.any inputs would be appreciated.

Thanks ,
M S K

[paolo bevilacqua]

Answered above already by Rober and myself: you have to work with the phones vendor, because network does not cause echo.

[slashdots]

I often experience following reasons for echo:

- Faulty headset

- People are using speakerphone

Because you are using polycom phones, I strongly recommend you to contanct your phone systems vendor.