I've seen request for NAT transversal solutions & utilities such as STUN and ICE. I deal with these issues on a daily basis at my professional place of work as an ITSP/ISP provider. Our Genband class-5 switch has a SIP implementation that cant handle NAT transversal very well. So you would have SIP ATAs that would randomly drop registrations or have 1-way audio due to the customer's NAT device and/or firewall. We invested into the Covergence CXC SBC product as a result. They've worked flawlessly and give us much better control than the Genband can offer alone. Covergence also suppplies Vonage's SBCs. I'm thinking the Elastix Developers should take a look at http://www.opensourcesip.org has to offer for OpenSBC. Typically an SBC sits between the VoIP box and the user and takes care of keeping the NAT transversal to the customer's ATA active. This may be an all-in-one solution that Elastix may integrate and provide a very powerful enterprise solution.