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Although I didn't receive any answers on this question I now know that on my Moto G2 phone, contacts are stored neither on the phone or Sim, but in Google Contacts. This means I can simply use the new SIM when it comes and still have all my contacts available. Not sure why but this phone seemingly has no option to store contacts on the phone or SIM, friends have LG and Samsungs phones that do have such options - I presumed all did. I'm happy though that all my contacts are somewhere "safe"