A woman called, heavy accent (sounded like an overseas call centre) and it was muffled, not very clear. She said she was from the Mastercard and Visa department (of what???). I figured it was a scam call, I stopped her and asked her to speak clearer because she was muffled. She said "Can you hear me?" I replied "Yes, but you're muffled, you sound like you're speaking through a sock." She hung up. I called the mobile number straight back, and got a voicemail with an Aussie male voice. I didn't leave a message, but called the number again until it was answered by the Aussie male. It appears his mobile number has been hijacked and is being used by some scammers - he's received other calls from people about it, too.