SIP will NOT be the only protocol for IP Communications, at least not from the perspective of purists. Like a parent who cannot recognize his own children, SIP will spawn children that we cannot even foresee. This said, H.323 also is alive and well, as is MGCP and Megaco. But SIP will dominate new services and features. Although VoIP really came into the public spotlight by delivering cheap minutes, my expectation that it would gain a foothold and then transition into novel services has been proven correct.
Arbitrage is dead.
The instant messaging and presence space represents the future of communications services. The Internet, just as in 1998, continues to lack QoS. Thus, while I encourage companies to start using the various IP call center applications finally reaching maturity, they will have to carefully manage their network traffic to make sure the basic voice service is not diminished. As I predicted, the regulation of Internet telephony has and will accelerate movements off of the PSTN and onto VPNs. Requirements like E911 will force into the place the infrastructure for new services, and bills attempting to strangle innovation will still require fighting. I thought the IP PBX would flower in late 1998.