Okay so i have AT&T and I had an iPhone and i had my voicemail setup for that...and i took my sim card out of that and put it in my old black jack...now every time i try to listen to my voicemails ill call my own number and it will sya please leave a message...and when i go to voicemails it says i need to enter my "voice mail box number" what do i do? i dont know my voice mail box number