I had hte same issue porting a number from Vonage (Address Validation) which then pushed out the original date and cost me another month of service with Vonage.

I since have kept the Vonage number at VoiPo but my other number (ported from AT&T) I've moved back to AT&T due to reliability issues with VoIPo. I don't know if it was the fact that I had 2 of their Grandstream adapters behind a router or if it was the whole continual registration issues for the month of February.