Trying to schedule a meeting with a client is always a challenge as they cannot see your availability and you cannot see theirs as we are on separate calendar/mail systems. I recently moved to Office 365 and clients that I work with have their own internal Exchange 20xx implementation (or some other system).
Now, with Office 365, there’s a way to publish your availability (free/busy) information with the world (see this: http://office.microsoft.com/en-us/outlook-help/share-your-office-365-calendar-RZ103433663.aspx - Look for “Setup the Publishing option). I imagine it is available with Exchange 2010/2013.
However, for a user in your client organization to review this calendar through a browser and then trying to figure out available time slot still doesn't provide the best user experience.
A better way would be for them to simply open this calendar in their Outlook as if it is yet another calendar.
To enable an external user (outside your organization) to open your calendar, the Office 365 calendar URL needs to be in the form of webcal ending in “.ics”. This is simple to achieve.
All you have to do is take the Office 265 calendar URL which is shared to the public, change the https:// to webcal:// and change the “.htm” at the end to “.ics”.
Give this URL to your clients. Let them go to Outlook Calendar and click on the “Open an Internet Calendar”. There they can paste this URL and Outlook will open this calendar.
Now, you can view my availability easily (and schedule meetings - sigh)!