SIP Trunking is a reality, although some end users believe its a myth based on the complexity of implementing SIP trunks on their legacy systems. I would argue that SIP trunks are not only an up and coming replacement to the TDM and analog trunking options we have known for so many years, but they are also a great strategy for disaster recovery in the cloud for dial-tone and cost effective back up to the TDM and analog trunks used today.
The difference is in your platform and how well it works with SIP providers. Many “pure” IP Telephony platforms, such as ShoreTel, can support native SIP trunks to their system. Products like the InGate SIPerator, a gateway to help with compatibility to SIP providers networks for IP PBX’s, are also certified with ShoreTel and can allow for users to connect with all types of SIP providers. At Liquid, we subscribe to a SIP provider and keep all our inbound and outbound traffic in the cloud out of our hosted facility.