Squealing on IP phones

[TBLuk]

We're experiencing intermittant squealing, only audible to 'non-IP' parties in the call.

So, if someone makes a call into this site, only they hear the squealing.
If someone makes a call out of this site, only the other party hears this squealing.

This squeal is loud, piercing and almost damaging to hearing!

Running the G.711 codec, never used to happen on G.729.

MD110 recently upgraded to BC12 SP10, from SP7 but problem still persists.

Any ideas?

 

[aastratech]

TBLuk,
can you confirm the ELU32 and IP phone software you are running?

 

[TBLuk]

mdevo,

Phones are generally DBC425 running R2B hardware, R5G software, and R5E BootRom.

ELU32s are ROF1375428/1 and are running R7A.

Any ideas from anyone appreciated

 

[whosrdaddy]

sounds like you have serious jitter problems upstream.

try to test the network link between the 2 sites. Use a program like chariot to see if Qos working downstream and upstream...

-----------------------------------------------------
What You See Is What You Get
Never underestimate tha powah of tha google!

 

[TBLuk]

Hey,

I'm not convinced it is jitter to be honest. The VoIP element is only on the local switch. There is no VoIP traffic travelling over any serial interfaces. The MD110 LIM is local. (Although it in itself is a remote LIM, all ELU32s are in this remote LIM)

 

[whosrdaddy]

ok, what about Qos then??

-----------------------------------------------------
What You See Is What You Get
Never underestimate tha powah of tha google!

 

[TBLuk]

This is what I'm checking next, I just have to rule out the MD110 side as our data and voice technical support is split over two teams.

Was really just posting here to see if anyone has experienced it, i.e. is it a known problem often on Ericsson VoIP.

Given that the phones and cards are at the latest firmware, it seems that QoS/codecs may be to blame. No CAC is set, which I disagree with.

 

[whosrdaddy]

I have several customers running that firmware without any problem... Qos is the magic word here.

-----------------------------------------------------
What You See Is What You Get
Never underestimate tha powah of tha google!