VoXaLot and FWD: sound issues when calling FWD

[f7391]

I noticed an interesting issue with Free World Dialup (FWD): when calling to FWD account via VoXaLot using VoXaLot account (the VoXaLot speed dial functionality) and a SIP phone the FWD.communicator on laptop will alert and if answered, I can hear the voice from SIP phone but no voice from the FWD.communicator account gets to SIP phone. If I call from FWD account to VoXaLot account everything works just fine.

I've even tried this using public ip's so both the SIP phone and laptop running FWD.communicator have a public ip without NAT, firewalls or whatever and still with same result. I even tried this with Windows XP firewall disabled but the result was same. This is quite strange, does someone have suggestions how to get this thing working or is this a known issue?

As using FWD is not really a strict requirement for me, I would be very happy if someone could propose a good general usage SIP client for Windows?