Ok, After applying th SYSCFG settings, the SIM is now registered in the network.
Examples:
AT^SYSCFG=2,1,3FFFFFFF,1,2 for GPRS/EDGE Preferred
AT^SYSCFG=2,2,3FFFFFFF,1,2 for 3G Preferred
AT^SYSCFG=13,1,3FFFFFFF,1,2 for GPRS/EDGE Only
AT^SYSCFG=14,2,3FFFFFFF,1,2 for 3G Only