How to minimize iPhone data traffic using MobileMe

Aug 08, '08 07:30:01AM

Contributed by: Anonymous

Here are my conclusions so far based on a series of packet sniffing experiments to understand how much data is used by the iPhone.

The most conservative data use sync options are to turn the master "push" switch off, and to set the fetch settings to manual. When that happens, calendars and contacts seem trigger an immediate sync when new items are added. Otherwise, there is no apparent periodic traffic unless you trigger a manual sync (done by entering the application itself.)

You can usually trigger a manual sync by entering the application whose data you want to sync. With the conservative settings, exiting and entering an application (contacts, calendar, etc) seems to remind the iPhone to check for new data from MobileMe. If the phone hasn't recently checked for a few minutes, over the next 10 to 15 seconds, the phone will reach out over the network and poll for updates. For instance, if at 5:52pm you enter the calendar application and update data, you will trigger a sync. But if at 5:54pm you enter the application again, you will not trigger any network traffic. If you enter at 5:55pm you get a sync.

Once you've triggered a sync (for whatever reason), all updates for the application are exchanged with MobileMe. Updates apply only to that application, so a sync on contacts does not necessarily update calendars.

Even polling for new data is expensive -- I typically measured 5KB to 6KB in traffic for an empty poll to check if data had changed.

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