Bad signal quality with Voxalot and others (Grandcentral, IPKall, Gizmo)

[Cris77]

Hi everybody,

Thanks in advance for the support . It is wonderful to have a community so willing to help.

The problem is that the quality of my calls is not good at all . They are usually broken. Especially people on the other side, cannot hear me well.

This is my current configuration:

Income :
Grandcentral -> IPKall -> Voxalot -> My voip phone

Outgoing:
Grandcentral -> IPKall -> Voxalot -> My voip phone (call from the site)
or My voip phone->Voxalot->VoipDiscount

The hardware that I am using is a Fonera with DD-wrt v24 RC2 (the newer versions are not stable for me).
I had prioritized the QoS for my VOIP phone MAC address and also the sip protocol has been prioritized.
I tried to reduce the outgoing bandwidth in QoS from 512k to 486k without any improvement.

The echo test *600 is (usually) good but not always.

I tried to set Symmetric NAT Handling to 'No' and then I had no audio.

I have tried to replace IPKall with Gizmo as bridge between Grandcentral and voxalot forwarding the calls to my number xxxxxx@us.voxalot.com:
Grandcentral -> Gizmo -> Voxalot -> My voip phone

but if I try to initialize the call from Grandcentral, my voip phone rings but when I answer there is no audio.

May it be a codec problem? How do I solve it?

Best,
Cris