Looking for good hosted Business IM

[darrensmith]

Hi All.

I have been scouring the internet and I am pulling my hair out!
I have a management consultancy in South Africa, and for many reasons, all of my companies software run as hosted SAAS (software as a service) solutions. Which means I do not have any IT infrastructure. We prefer the pay per user per month model.

I am looking for a dedicated IM solution for my business as we are presently using Skype chat, but I am looking for a dedicated, secure company wide IM platform, that can be hosted by someone else. I also need a cross platform client as we run a mixture of Mac and Windows clients.

Any Ideas??