Has anybody else made more progress with this? I set things up the same way on my E61i and the phone registered with Vonage but I get the same "Address not in use" error message when attempting to place an outbound call. Also, the phone rings when calling the Vonage softphone number but it doesn't answer the phone when I press the answer button. It seems that people have been able to get the built in VoIP client working with other providers so I'm assuming it's either unique to Vonage or my configuration. Thanks.