There's nothing preventing someone from throwing garbage into the SS7 network, it's just that as has been repeated already several times, the barriers to entry for that rather exclusive, proprietary and expensive world are rather high. The issue with setting up a secure and trusted signaling plane over the Internet isn't so much making the communication pathways secure; VPNs do a perfectly good job of that. That's not the problem. The problem is the security of all the other things that are also connected to the IP network into which those VPN tunnels land. If an ordinary server is broken into, it can be used as a jump-off point by someone who knows what they're looking for to compromise the signaling plane as well by forwarding packets through the right gateway destination. No, it's not terribly easy, but at the same time, the chances of it happening are orders of magnitude higher in a generalised IP scenario. That's much harder to do with SS7 endpoints; one would have to break not only into a network element via IP, but also stick an exploit into what is usually a very proprietary and reasonably secure black box. The other related factor is that as many participants in the SS7 network as there are, that's a very, very small pool of deployments, generalised user experience and far-reaching knowledge as compared to anything IP. Ubiquitous operating systems and open-source packages enjoy thousands of times the volume of bugs, cracks, exploits and open QA feedback on which there is a lot of sunshine as compared to something so exclusive. That's not to say that there isn't already plenty of SS7 over public IP going on. I've seen more than my fair share of CLECs - usually little ones created to support the back side of some VoIP product - interconnect with the ILEC via SIGTRAN over Internet VPN to a third-party provider that actually works the A-links. I don't know if VeriSign still offers this product, but it was plenty popular. -- Alex -- Alex Balashov Evariste Systems Web : http://www.evaristesys.com/ Tel : (+1) (678) 954-0670 Direct : (+1) (678) 954-0671 Mobile : (+1) (678) 237-1775