I have been watching the SBC segment grow at an impressive pace over the last few years. I think the widespread deployment of SBCs highlights the fact that standards are not much of an issue in the new communications industry. Carriers possess the necessary confidence to implement a non-standard solution for problems to which they seek immediate solutions. SBC has no strict definition in any blueprint or a standard. And yet it is deployed worldwide.
Often in the standards there is room for interpretation at some level. For example within SIP, vendors do not implement it the exact same way. There are many H.323 variants too. So standards are not much of an issue. The issue is, for example, what version of 323 does a vendor need to interoperate with. Vendors need to implement the standard. But more importantly they need to test and interoperate with other equipment. And that is where the challenges are.
Deploying a VoIP service involves deploying more than a SBC. There are softswitches, media gateways, media servers, application servers, end points etc. In all cases the initial schedule is hardly kept and it is usually the interoperability issue that causes delays.