When using cloud UC services, SMBs offload the upfront capital expenditures associated with buying an IP PBX/call server and software licenses to the UC hosted service provider. They also avoid the cost of technology refreshes. Cloud solutions enable SMBs to get the features and capabilities they need over the Internet, rather than installing and maintaining their own UC infrastructure incurring greater real estate, energy and staffing costs.
With a hosted VoIP phone system, only the phones are located in your office. The costs and responsibility of powering, maintaining, and supporting the phone system are covered by the provider and managed remotely. You only pay for the services that you need on a per user basis, and you can even purchase or lease the phones as well. By leveraging the expertise and hands-on monitoring of a hosted PBX provider , your business can rest easy knowing that you have a trusted partner functioning like part of the team, allowing your internal technical staff to focus on other projects.
Here is a really good article on Why hosted Solutions for your phone system and the comparisons to a traditional Premised based solution.