yes, I have vast experience in VoIP, have tested (worked) with many softswitches and billing systems.
I can fully declare that SM/VM is a crappy product. Or at least – it was such one. Since some time I am doing my best to stay away from it.
Even worse, SM/VM is not only a crap, but a STOLEN crap. I think that you know what SM/VM is built on – stolen GnuGK, stolen Asterisk (though I heard that they agreed to pay something to Digium) and stolen SyBase.
Who (a person in his right mind) would buy such a thing ?