Obviously there are various opinions but there is nothing like real people giving real face.
Responding to your question about Sysmaster, I have 3 prepaid calling card people:
Rani Phone (Velo Solutions Canada) and myself and a parend company that we are working with Sysmaster for already 1 year.
For the price you get a unique product capable of managing both retail and wholesale traffic.
I got so far connected 1 thousand simultaneous calls and the product responds good, the billing syncs and the hability to provide me a friendly graphic user interface is great.
I have never spoken bad about a product because I think that every product has an specific market and service area, so far Sysmaster has proven to be very reliable and due to the fact that manages signaling H323 and SIP allows calls to connect without using bandwitdh resources, for those that are trying to get into the retail business of prepaid calling cards and the ones that are in the broker arena, this equipment is a life saver.
you receive calls as a gateway, manage calls as a gatekeeper, route like a softswitch and redirect again as a gateway including billing in many flavors and variants on the same box.
So fat they say the box handles 2,000 simultaneous calls, I have tested 1,000 max and the equipment is running well in resources.
I am colocated at the Nap of the americas terremark in Miami ,FL and most of my traffic is to South and Central america.
For those that really want to get a real idea of this equipment and how I use it making good profit.