ZeeBOB: We also use CallPlus for our company and are experiencing severe speed issues to Office365 and Microsoft CRM Online.
A contact at M$ told me they were going to procure dedicated bandwidth to NZ to improve the speeds for NZ to Microsoft Hosted Services sometime in early 2013. Sounds like its gotten worse not better.
what sort of connectivity do you have with callplus - fibre? and are you using and wan accelerator firewalls?