8x8

Pros -   8x8 integrates with applications such as Salesforce, SugarCRM and Outlook, allows you to include up to 20 conference call attendees and provides unlimited calling plans to 10 countries.
Cons -  This service lacks many advanced queuing options, however they do offer call ring groups to handle excess calls. 
The Verdict -  7.95/10With great customer and technical support, several calling plans, and fail-safe, redundant solutions to ensure reliable service with zero downtime, 8x8 has covered all their bases to provide a good business VOIP solution.