I have a BlackBerry Z3, I lost it, found it and got it unblacklisted. Why am I still getting the error code mm#6?

If I insert my sim card to another phone it works properly to show that the problem is not with the sim card

have you called your carrier?

"Unblacklisting" is not an easy thing to get done. Make sure your phone really is "unblacklisted" at your SIM's carrier.