I have a curve 3G from fido/rogers, I had a rogers sim card in it for awhile but nvr activated the phone is it?

Locked to rogers? Becuz I went to koodo and got my sim card w/koodo, now it is asking me for a mep code what for koodo or my old rogers sim? becuz wen I start up my phone with the koodo sim card it says "your current SIM card requires an unlock code, do you want to unlock it? But I didn't receive an unlock code. Can any1 help me?