MobileDay requires that an in-country dial in number is contained in the invitation in order for the app to identify the meeting as a call and present a "join the call" button. Otherwise the user will get the message that "this event is not a call". The best solution is for the meeting organizer to include a dial in number for each country attendees will be joining the call from.
An alternative if the invite does not contain a dial in number is for you to set up and save a guest conference service for the recurring meetings that you join.
The way to set that up is to go to menu>Conference Services and tap "New" in the upper right hand corner, then select "Guest". Next add the in country dial in number you use and the guest conference number.
When it is time to join the meeting, you can join the call with one touch dialing from the Quick Call tab. To do that you tap the "Contacts" logo which is the far right of the three logos at the top of the screen. Then on the next row that pops up tap the "Quick Call" logo on the far left and you will see your saved guest and host conference services. If you tap on the "Phone" icon at the far right of your saved guest conference service it will join you to that dial in number and meeting number with one touch dialing.