Why is my phone adding 61 prefix to contacts

[Android Central Question]

I have a samsung galaxy s7 with pre paid sim. I save a contact with 02 prefix for a interstate landline no. When i try to dial the contact the call wont go through. When i look at my call log the no called has a 61 prefix. How do i stop my phone from automatically adding 61 to a contacts no when I call it. I have noticed all numbers in my call log have 61 added even though i havent added it when creating the contact. In each contacts info the 61 doesnt show