Lots of businesses are using Google Apps, and with good reason. Google Calendar streamlines schedule coordination and is especially vital to use with sales prospects because the opportunity cost of getting a timezone wrong or having a prospect fail to show up is too high.
However, the Google approach still has a couple problems. First, Google Hangout is possibly the single worst way to have a call due to all kinds of plugin and permission issues. If the user could be invited with an email address from a secondary account, they may be unable to join. There are also hardware/audio/video issues, echoes, poor connections, etc. In short, Google Hangouts is a great way to completely fail the call.
If you choose to use another service, invitees can be really confused when they get an invitation to a GoTo Meeting event because Google auto-adds hangout links to calendar invitations. Which are they supposed to open?
There is a solution. Instead of Hangouts, use phone, join.me, or gotomeeting – something that has good audio quality, allows direct dial-in, and doesn’t require any plugins to be installed by default.
Still use Google Calendar invitations, but disable auto-adding of hangouts. That way, you can still manually add if desired, but it is not automatic.
This requires the domain admin to disable it on a domain-wide basis. From admin.google.com, go to Apps, find Calendar, select Sharing Settings, and uncheck the “Automatically add video calls” checkbox at the bottom. For more details see https://support.google.com/a/answer/4362302.