Trying to delete phone numbers from a mobile phone shouldn't be a a hair pulling, teeth grinding and rage building excercise.
Thats where I ended up after attempting to rid my phone of all the rubbish numbers it's accumulated over the past year or so.
Here are a couple of default unlock codes that I ended up needing:
For a Vodafone SIM: 12345
For a Sony Ericsson T610: 0000