I have used sysmaster now for a good while. While, on the surface it seems to represent good value for money, I reckon its a terrible platform due to the non-existent support for it. Their attitude to support is autocratic: refusing to even look in depth at your system to analyse a problem, always eager to blame an obvious problem on a need for extra modules, selling you modules with no description and documentation, and generally not caring a dime about customers. If you base your business on this platform, well, you do so at a great risk to your business.
Voicemaster was the first system I have ever come across in my lengthy history with IT and telecoms, where the customer is always wrong, and where the customers entire operations being down does not stimulate eagerness to assist the customer to resolve their problems .