The `sim_contacts` is different than `all_contacts`.
The `all_contacts` uses `navigator.mozContacts.find({})` to get the contacts in device, and the `sim_contacts` uses `navigator.mozContacts.getSimContacts('ADN')` to get the contacts in SIM card.
Ref: [gaia_data_layer.js](https://github.com/askeing/gaia-ui-tests/blob/test_import_from_sim/gaiatest/atoms/gaia_data_layer.js#L26)