Never had to unlock a phone before so would appreciate a tip or 2 please! Have 3 well worn unlocked Blackberries from new and have now got a nearly new 9900 from a friend which appears to be locked to Vodaphone. Have put a spare PAYG Tesco SIM in, (which works for phone / texts on other Blackberries) to test. The home screen says 'Invalid SIM'. Advanced options says SIM Disabled which my web searches suggest that the phone is unlocked. Confused!