1. O2 Joggler cannot create O2 calendar.
You should have PC, O2.co.uk accout and calendar creation via PC before use of O2 calendar at O2 Joggler which means O2 Joggler user with no PC cannot use O2 calendar.

2. O2 Joggler cannot add new member for O2 calendar.
You have to use PC for add new member.

3. There is no popup reminder for registered schedule at O2 Joggler.

4. You cannot set the end date/time for schedule.

5. Receive reminder, view/update schedule by mobile is only for O2 modile. Non-O2 mobile cannot use these.

6. O2 calendar does not have e-mail remider.

7. No export/import the calendar data for other calendar.

8. No coordination functionality with other WEB service like as calendar + map.

9. O2 calendar cannot be use at off line.

10. Like as O2 account name, you cannot create same O2 calendar name which somebody else already use.

11. You cannot use space in O2 calendar name.

12. O2 iPhone should have special version of O2 calendar but not. Does O2 suggest to O2 iPhone user to use Google calendar?

13. You cannot create secret schedule. All member of your O2 calendar can see your all schedule.