I am working on an app that syncs device contacts with a server and I stumbled across this situation.
Sim card contacts are not being aggregated with the rest of them so every time a sync is performed, the syncAdapter finds them as a new contact and sends them to the server.
On my android device, (s5 - 5.0), in the Phone app, you can import contacts from sim to different accounts, but they will appear as duplicates. So clearly they have a special situation.
How could I avoid back-to-back syncing without avoiding the sim contacts?