[Asterisk-Users] Sipbroker?

[Matt]

Has anyone heard of or used sipbroker?
http://www.sipbroker.com/sipbroker/action/login

I was doing some brief looking around with them, and tried their PSTN
gateway, but was unable to get it to complete to calls with providers
such as at vonage (Where they claim I can peer).
I did an enum search for several Vonage numbers and none showed up in
enum.   I'm confused.  What's the point?  If the end user has to
register their number as being with provider XYZ, this is almost
not-useful.  Can anyone explain or clear this up for me?