Obviously SIP is considerably better than H.323 and complies with the understanding of IP-telephony as a global mass IP-service, and it should be implicitly considered right this way. And as SIP is able to serve not only telephony but also any communications at all in the real time over the IP-protocol; obviously it should become a base for other IP-services not yet existing but will appear in the future, as well.
Spirited Broadband provides Business class services either by tradional circuitry or via IP. SBB specializes in trunking existing PBX`s and will be happy to serve your Business needs today.