The big vendors in the market used to be Tekelec and DSC. DSC was eaten by Alcatel, if I remember right -- but Tekelec had just rolled out new products that were more or less wiping the floor with everyone else, integrating enough SCP functionality into their Eagle STP to do local number portability and a range of other high-volume applications.
Of course there were other platforms out there like the Lucent one, mostly deployed at AT&T, and Nortel's offering, about which I know very little -- and there were actually a few networks out there using Tekelec's MGTS SS7 test appliance as an STP, which is a little crazy but I've seen it work.
That was almost 10 years ago, about when I got out of the SS7 business. I am not sure what's happened since then (I'd assume further consolidation, as well as probably some business siphoned off by SS7 over IP type boxes) and in fact I'd be curious to know.
Thor Lancelot Simon snipped-for-privacy@rek.tjls.com
"The inconsistency is startling, though admittedly, if consistency is to be abandoned or transcended, there is no problem." - Noam Chomsky